Compilare: user.cpp: In function ‘int main()’: user.cpp:84:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<C.size();++i) ^ user.cpp:89:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (printf("%d\n",C.size()),i=0;i<C.size();++i,printf("\n")) ^ user.cpp:52:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("retele.in","r",stdin); ^ user.cpp:53:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("retele.out","w",stdout); ^ user.cpp:55:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (scanf("%d%d",&N,&M);M;--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); ^