Compilare: user.cpp: In function ‘void GrDfs(int)’: user.cpp:19:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < Gr[X].size(); i++) { ^ user.cpp: In function ‘void TrDfs(int)’: user.cpp:33:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < Tr[X].size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:63:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < Ctc.size(); i++) { ^ user.cpp:64:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < Ctc[i].size(); j++) { ^ user.cpp:43:29: 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:44:31: 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:46:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &M); ^ user.cpp:48:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &X, &Y); ^