Compilare: main.cpp: In function 'void df(int)': main.cpp:13:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<G[x].size(); i++ ) ~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:21:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("dfs.in", "r", stdin); ^ main.cpp:22:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("dfs.out", "w", stdout); ^ main.cpp:24:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &n, &m); ^ main.cpp:28:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &x,&y); ^