Compilare: user.cpp: In function ‘int main()’: user.cpp:75:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<S.size();++ i) ^ user.cpp:77:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i+1<S.size() && S[i].first==S[i+1].first) ^ user.cpp:48:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(infile,"r",stdin); ^ user.cpp:49:24: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(s,MAXN,stdin); ^