Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:19:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < con[nod].size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:62:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < ww.size(); i++) { ^ user.cpp:63:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j = 0; j < ww[i].size(); j++) { ^ user.cpp:47:34: 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:48:36: 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:49:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &M); ^ user.cpp:52:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^