ADDED   SRM/708-U/1A.cpp
Index: SRM/708-U/1A.cpp
==================================================================
--- SRM/708-U/1A.cpp
+++ SRM/708-U/1A.cpp
@@ -0,0 +1,114 @@
+#include <iostream>
+#include <sstream>
+#include <iomanip>
+#include <vector>
+#include <string>
+#include <map>
+#include <set>
+#include <algorithm>
+#include <numeric>
+#include <iterator>
+#include <functional>
+#include <complex>
+#include <queue>
+#include <stack>
+#include <cmath>
+#include <cassert>
+#include <tuple>
+using namespace std;
+typedef long long LL;
+typedef complex<double> CMP;
+
+class BalancedStrings { public:
+	vector <string> findAny(int N)
+	{
+		return solve(N);
+	}
+
+	int sim(const vector<string>& S) {
+		int cnt = 0;
+		for (int i = 0; i < S.size(); ++i)
+			for (int k = i + 1; k < S.size(); ++k)
+				for (char c1 : S[i])
+					for (char c2 : S[k])
+						if (c1 == c2)
+							++cnt;
+		return cnt;
+	}
+
+	vector<string> solve(int N)
+	{
+		if (N <= 26) {
+			vector<string> ans;
+			for (int i = 0; i < N; ++i)
+				ans.push_back(string(1, 'a' + i));
+			return ans;
+		}
+
+		vector<string> ans;
+		for (int i = 0; i < N-2; ++i)
+			ans.push_back(string(1, 'e' + i%20));
+		int s = sim(ans);
+		string a = "b";
+		string c = "d";
+		while (s && a.size() < 100) a += (a.back()=='a' ? 'b' : 'a'), --s;
+		while (s && c.size() < 100) c += (c.back()=='c' ? 'd' : 'c'), --s;
+		ans.push_back(a);
+		ans.push_back(c);
+		return ans;
+	}
+};
+
+// BEGIN CUT HERE
+#include <ctime>
+double start_time; string timer()
+ { ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
+template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
+ { os << "{ ";
+   for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
+   os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
+void verify_case(const vector <string>& Expected, const vector <string>& Received) {
+ bool ok = (Expected == Received);
+ if(ok) cerr << "PASSED" << timer() << endl;  else { cerr << "FAILED" << timer() << endl;
+ cerr << "\to: " << Expected << endl << "\tx: " << Received << endl; } }
+#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
+#define END	 verify_case(_, BalancedStrings().findAny(N));}
+int main(){
+
+CASE(0)
+	int N = 3; 
+	string __[] = {"eertree", "topcoder", "arena" };
+	  vector <string> _(__, __+sizeof(__)/sizeof(*__)); 
+END
+CASE(1)
+	int N = 4; 
+	string __[] = {"hello", "little", "polar", "bear" };
+	  vector <string> _(__, __+sizeof(__)/sizeof(*__)); 
+END
+CASE(2)
+	int N = 5; 
+	string __[] = {"abbbbbbbbbbbbczaaaaaao", "c", "zz", "c", "xxxyyyzvvv" };
+	  vector <string> _(__, __+sizeof(__)/sizeof(*__)); 
+END
+CASE(3)
+	int N = 1; 
+	string __[] = {"kkkkkkkkkkkkkkkkkkk" };
+	  vector <string> _(__, __+sizeof(__)/sizeof(*__)); 
+END
+CASE(4)
+	int N = 10; 
+	string __[] = {"asdflkjhsdfsfffkdhjfdlshlfds", "pudelek", "xo", "xo", "mnbvmnmbbr", "plox", "qqwwrrttyyy", "you", "are", "awesome" };
+	  vector <string> _(__, __+sizeof(__)/sizeof(*__)); 
+END
+CASE(5)
+	int N = 100; 
+string __[] = { "" };
+	  vector <string> _(__, __+sizeof(__)/sizeof(*__)); 
+END
+CASE(6)
+	int N = 40; 
+string __[] = { "" };
+	  vector <string> _(__, __+sizeof(__)/sizeof(*__)); 
+END
+}
+// END CUT HERE

ADDED   SRM/708-U/1B-U.cpp
Index: SRM/708-U/1B-U.cpp
==================================================================
--- SRM/708-U/1B-U.cpp
+++ SRM/708-U/1B-U.cpp
@@ -0,0 +1,145 @@
+#include <iostream>
+#include <sstream>
+#include <iomanip>
+#include <vector>
+#include <string>
+#include <map>
+#include <set>
+#include <algorithm>
+#include <numeric>
+#include <iterator>
+#include <functional>
+#include <complex>
+#include <queue>
+#include <stack>
+#include <cmath>
+#include <cassert>
+#include <tuple>
+using namespace std;
+typedef long long LL;
+typedef complex<double> CMP;
+
+static const unsigned MODVAL = 1000000007;
+struct mint
+{
+	unsigned val;
+	mint() :val(0) {}
+	mint(int      x) :val(x%MODVAL) {}
+	mint(unsigned x) :val(x%MODVAL) {}
+	mint(LL       x) :val(x%MODVAL) {}
+};
+mint& operator+=(mint& x, mint y) { return x = x.val + y.val; }
+mint& operator-=(mint& x, mint y) { return x = x.val - y.val + MODVAL; }
+mint& operator*=(mint& x, mint y) { return x = LL(x.val)*y.val; }
+mint operator+(mint x, mint y) { return x += y; }
+mint operator-(mint x, mint y) { return x -= y; }
+mint operator*(mint x, mint y) { return x *= y; }
+
+template<typename T>
+struct DP2
+{
+	const int N1, N2;
+	vector<T> data;
+	DP2(int N1, int N2, const T& t = T())
+		: N1(N1), N2(N2), data(N1*N2, t) {
+		assert(data.size() * sizeof(T)<(1 << 28));
+	}
+	T& operator()(int i1, int i2)
+	{
+		return data[(i1*N2) + i2];
+	}
+};
+
+class PalindromicSubseq { public:
+	int solve(string s)
+	{
+		const int N = s.size();
+
+		DP2<mint> outer(N, N), inner(N,N);
+		for (int l = 0; l < N; ++l)
+			for (int r = l; r < N; ++r)
+				if (s[l] == s[r])
+					outer(l, r) = inner(l, r) = 1;
+
+		for(int len=N; len>=1; --len)
+			for (int l = 0; l+len-1 < N; ++l) {
+				int r = l + len - 1;
+				if (s[l] == s[r]) {
+					for (int x = l - 1; x >= 0; --x)
+						for (int y = r + 1; y < N; ++y)
+							if (s[x] == s[y])
+								outer(l,r) += outer(x, y);
+				}
+			}
+		for (int len = 1; len <= N; ++len)
+			for (int l = 0; l+len-1 < N; ++l) {
+				int r = l + len - 1;
+				if (s[l] == s[r]) {
+					for (int x = l + 1; x < r; ++x)
+						for (int y = r - 1; y >= x; --y)
+							if (s[x] == s[y])
+								inner(l,r) += inner(x, y);
+				}
+			}
+		vector<mint> X(N);
+		for (int l = 0; l < N; ++l)
+		for (int r = l; r < N; ++r)
+			if (s[l] == s[r]) {
+				mint total = inner(l, r) * outer(l, r);
+				X[l] += total;
+				if (l != r) X[r] += total;
+			}
+
+		int ans = 0;
+		for (int i = 0; i < N; ++i)
+			ans ^= ((i+1)*X[i]).val;
+		return ans;
+	}
+};
+
+// BEGIN CUT HERE
+#include <ctime>
+double start_time; string timer()
+ { ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
+template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
+ { os << "{ ";
+   for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
+   os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
+void verify_case(const int& Expected, const int& Received) {
+ bool ok = (Expected == Received);
+ if(ok) cerr << "PASSED" << timer() << endl;  else { cerr << "FAILED" << timer() << endl;
+ cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
+#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
+#define END	 verify_case(_, PalindromicSubseq().solve(s));}
+int main(){
+
+CASE(0)
+	string s = "aaba"; 
+	int _ = 30; 
+END
+CASE(1)
+	string s = "abcd"; 
+	int _ = 4; 
+END
+CASE(2)
+	string s = "tcoct"; 
+	int _ = 60; 
+END
+CASE(3)
+	string s = "zyzyzzzzxzyz"; 
+	int _ = 717; 
+END
+CASE(4)
+	string s = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"; 
+	int _ = 1025495382; 
+END
+CASE(5)
+	string s = "a";
+	int _ = 1;
+END
+CASE(6)
+	string s = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
+	int _ = -1;
+END
+}
+// END CUT HERE