Compilare: user.cpp: In function ‘int main()’: user.cpp:41:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=1;j<B.size();++j) ^ user.cpp:49:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(B.size()==n+m-1)break; ^ user.cpp:52:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<B.size();++i) ^ user.cpp:16:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bemo.in","r",stdin); ^ user.cpp:17:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bemo.out","w",stdout); ^ user.cpp:18:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:25:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^