Compilare: user.cpp: In function ‘int Solve(std::vector<int>, std::vector<int>)’: user.cpp:38:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<it->second.size();i++) ^ user.cpp:44:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<it->second.size();i++) ^ user.cpp:49:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<it->second.size();i++) ^ user.cpp:9:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j,line=-1,answer=1,forced=-1; ^ user.cpp: In function ‘int main()’: user.cpp:55:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("entanglement.in","r",stdin); ^ user.cpp:56:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("entanglement.out","w",stdout); ^ user.cpp:58:44: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&requirement,&n,&m,&k); ^ user.cpp:61:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&c[i][j]); ^