Compilare: user.cpp: In function ‘int main()’: user.cpp:57:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i < x.first.size();i++) ^ user.cpp:53:24: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(s, 1003, fin); ^