Compilare: user.cpp: In function ‘int ins(int)’: user.cpp:10:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<h[t].size();i++) ^ user.cpp:13:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:17:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("facebook.in","r",stdin); ^ user.cpp:18:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("facebook.out","w",stdout); ^