Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:20:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<GN[nod].size(); ++i) ^ user.cpp: In function ‘int dfs2(int)’: user.cpp:29:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<G[nod].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:74:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<C[i].size(); ++j) ^ user.cpp:37:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biperm.in", "rt", stdin); ^ user.cpp:38:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biperm.out", "wt", stdout); ^ user.cpp:39:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^ user.cpp:45:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^