Compilare: user.cpp: In function ‘void DFS(int)’: user.cpp:27:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < Gr[X].size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:68:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < Ctc.size(); i++) { ^ user.cpp:69:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < Ctc[i].size(); j++) { ^ user.cpp:51:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in","r",stdin); ^ user.cpp:52:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out","w",stdout); ^ user.cpp:54:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &M); ^ user.cpp:56:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &X, &Y); ^