Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:116:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[x].size(); ++i) { ^ user.cpp: In function ‘void solve(int, int)’: user.cpp:138:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[x].size(); ++i) { ^ user.cpp:152:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[y].size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:62:45: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("disconnect.out" , "w" , stdout); ^ user.cpp: In member function ‘char InParser::read_ch()’: user.cpp:30:38: 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); ^