Compilare: user.cpp: In function ‘int main()’: user.cpp:69:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < Comp.size(); ++ i) ^ user.cpp:71:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < Comp[i].size(); ++ j) ^ user.cpp:50:38: 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:51:40: 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:53:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i %i", &N, &M); ^ user.cpp:56:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i %i", &X, &Y); ^