#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 BearSpans { public:
vector <int> findAnyGraph(int n, int m, int k)
{
if(k>29 || (1<<k)>n)
return vector<int>(1, -1);
// generate basic
vector<int> ans = gen_base(1, 1<<k);
for(int p=1, v=(1<<k)+1; v<=n; p=v++) {
ans.push_back(p);
ans.push_back(v);
}
vector<vector<bool>> used(n+1, vector<bool>(n+1));
for(int i=0; i<ans.size(); i+=2) {
used[ans[i]][ans[i+1]] = true;
used[ans[i+1]][ans[i]] = true;
}
for(int s=1; s<=n && ans.size()<2*m; ++s)
for(int e=s+1; e<=n && ans.size()<2*m; ++e)
if(!used[s][e]) {
ans.push_back(s);
ans.push_back(e);
}
return ans;
}
vector<int> gen_base(int vS, int vE)
{
if(vS+1 == vE) {
vector<int> ans;
ans.push_back(vS);
ans.push_back(vE);
return ans;
}
int vM1 = vS + (vE-vS+1)/2 -1;
int vM2 = vS + (vE-vS+1)/2;
vector<int> a = gen_base(vS, vM1);
vector<int> b = gen_base(vM2, vE);
a.insert(a.end(), b.begin(), b.end());
a.push_back(vM1);
a.push_back(vM2);
return a;
}
};
// BEGIN CUT HERE
struct UnionFind
{
vector<int> uf, sz;
int nc;
UnionFind(int N): uf(N), sz(N,1), nc(N)
{ for(int i=0; i<N; ++i) uf[i] = i; }
int size()
{ return nc; }
int size(int a)
{ return sz[Find(a)]; }
int Find(int a)
{ return uf[a]==a ? a : uf[a]=Find(uf[a]); }
// Semi-compression w.o. recursion.
//{ while(uf[a] != a) a=uf[a]=uf[uf[a]]; return a; }
bool Union(int a, int b)
{
a = Find(a);
b = Find(b);
if( a != b )
{
if( sz[a] >= sz[b] ) swap(a, b);
uf[a] = b;
sz[b] += sz[a];
--nc;
}
return (a!=b);
}
};
int verify(vector<int> ans)
{
int m = ans.size() / 2;
int n = *max_element(ans.begin(), ans.end());
if(n == -1)
return -1;
vector<tuple<int,int,int>> cft;
for(int i=0; i<m; ++i)
cft.emplace_back(i+1, ans[2*i+0]-1, ans[2*i+1]-1);
vector<bool> added(cft.size());
UnionFind uf(n);
int LoopCount=0;
while(uf.size() > 1) {
vector<int> to_add;
vector<bool> done(n);
for(int e=0; e<cft.size(); ++e) if(!added[e]) {
int a = uf.Find(get<1>(cft[e]));
int b = uf.Find(get<2>(cft[e]));
if(a!=b) {
if(!done[a] || !done[b]) {
to_add.push_back(e);
done[a] = true;
done[b] = true;
}
}
}
for(int e: to_add) {
added[e] = true;
uf.Union(get<1>(cft[e]), get<2>(cft[e]));
}
LoopCount++;
}
return LoopCount;
}
#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 <int>& Expected, const vector <int>& Received) {
bool ok = (verify(Expected) == verify(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(_, BearSpans().findAnyGraph(n, m, k));}
int main(){
CASE(0)
int n = 17;
int m = 22;
int k = 1;
int __[] = {1, 2, 1, 3, 1, 4, 1, 5, 1, 6, 1, 7, 1, 8, 1, 9, 1, 10, 1, 11, 1, 12, 1, 13, 1, 14, 1, 15, 1, 16, 1, 17, 2, 3, 2, 8, 3, 9, 8, 9, 10, 12, 12, 14 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(1)
int n = 9;
int m = 12;
int k = 3;
int __[] = {6, 5, 7, 6, 1, 2, 3, 4, 8, 9, 3, 5, 7, 4, 1, 9, 6, 2, 6, 1, 1, 8, 4, 5 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(2)
int n = 9;
int m = 12;
int k = 7;
int __[] = {-1 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(3)
int n = 1000;
int m = 999;
int k = 970;
int __[] = {-1 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(4)
int n = 2;
int m = 1;
int k = 1;
int __[] = {1, 2 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(5)
int n = 3;
int m = 2;
int k = 1;
int __[] = {1, 2, 1, 3 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(6)
int n = 3;
int m = 3;
int k = 2;
int __[] = {-1 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
/*
CASE(7)
int n = ;
int m = ;
int k = ;
int __[] = ;
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(8)
int n = ;
int m = ;
int k = ;
int __[] = ;
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
*/
}
// END CUT HERE