Compilare: user.cpp: In function ‘void solve(int, int, int)’: user.cpp:62:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[nod].size();++i) ^ user.cpp: In member function ‘char InParser::read_ch()’: user.cpp:17:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, 4096, fin); ^