Compilare: user.cpp: In function ‘int main()’: user.cpp:37:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<V.size();i+=act){ ^ user.cpp:39:58: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(V[i+act].first == V[i].first&&i+act<V.size()) act++; ^ user.cpp:16:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pluton.in","r",stdin); ^ 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("pluton.out","w",stdout); ^ user.cpp:19:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld",&n); ^ user.cpp:21:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld",&x); ^