#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 <cstring>
#ifdef __GNUC__
#include <ext/hash_map>
#define unordered_map __gnu_cxx::hash_map
#else
#include <unordered_map>
#endif
using namespace std;
typedef long long LL;
typedef complex<double> CMP;
class LongestSequence { public:
int maxLength(vector <int> C)
{
vector<int> P, N;
for(int i=0; i<C.size(); ++i)
if( C[i]<0 )
N.push_back(-C[i]);
else
P.push_back(+C[i]);
sort(P.begin(), P.end());
sort(N.begin(), N.end());
if( P.empty() || N.empty() )
return -1;
int L = 0, R = 10000000;
while( R-L > 1 ) {
int C = (L+R)/2;
(has_loop(N, P, C) ? R : L) = C;
}
return L;
}
bool has_loop(const vector<int>& N, const vector<int>& P, int MAX)
{
vector<bool> vis(MAX+1, false);
queue<int> Q;
Q.push(0);
vis[0] = true;
while( !Q.empty() ) {
int v = Q.front();
Q.pop();
for(int i=0; i<N.size(); ++i)
if( v - N[i] == 0 )
return true;
else if( v-N[i] > 0 && !vis[v-N[i]] )
{vis[v-N[i]]=true; Q.push(v-N[i]);}
for(int i=0; i<P.size(); ++i)
if( v+P[i] <= MAX && !vis[v+P[i]] )
{vis[v+P[i]]=true; Q.push(v+P[i]);}
}
return false;
}
};
// 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(_, LongestSequence().maxLength(C));}
int main(){
CASE(0)
int C_[] = {-2,3};
vector <int> C(C_, C_+sizeof(C_)/sizeof(*C_));
int _ = 3;
END
CASE(1)
int C_[] = {524};
vector <int> C(C_, C_+sizeof(C_)/sizeof(*C_));
int _ = -1;
END
CASE(2)
int C_[] = {1, -1};
vector <int> C(C_, C_+sizeof(C_)/sizeof(*C_));
int _ = 0;
END
CASE(3)
int C_[] = {11,-7};
vector <int> C(C_, C_+sizeof(C_)/sizeof(*C_));
int _ = 16;
END
CASE(4)
int C_[] = {-227,690,590,-524};
vector <int> C(C_, C_+sizeof(C_)/sizeof(*C_));
int _ = 713;
END
CASE(5)
int C_[] = {273,752,-738,-34,863,-21,-532,-824,-170,-130,206,346,836,149,-374,-807,55,-859,640,-103,266,-716,963,-274,-654,-429,-512,595,-253,-32,790,-884,-974,975,-493,-979,-548,423,-242,-443,-132,-868,-374,-854,-15,476,-950,968,740,799};
vector <int> C(C_, C_+sizeof(C_)/sizeof(*C_));
int _ = -1;
END
CASE(6)
int C_[] = {3,4,3,3,1,4,4,-5,3,1,5,5,3,2,-1,-5,-4,2,-4,2,-2,-2,1,-5,4,-3,-3,4,2,-1,2,-4,1,4,-4,-2,4,-5,0,-4,5,3,-5,1,0,0,4,5,-5,-5};
vector <int> C(C_, C_+sizeof(C_)/sizeof(*C_));
int _ = -1;
END
}
// END CUT-1000 HERE