Compilare: user.cpp: In function ‘int main()’: user.cpp:78:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( i=0; i<Comp.size(); i++ ) ^ user.cpp:80:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( j=0; j<Comp[i].size(); j++ ) ^ user.cpp:82:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( j=0; j<Comp[i].size(); j++ ) ^ user.cpp:65:36: 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:66:38: 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:67:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:70:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x, &y); ^