Compilare: user.cpp: In function ‘int main()’: user.cpp:66:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( i = 0; i < sol.size(); ++i ){ ^ user.cpp:68:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( j = 0; j < sol[ i ].size(); ++j ) ^ user.cpp:50:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.in","r",stdin); ^ user.cpp:51:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.out","w",stdout); ^ user.cpp:55:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:57:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^