Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:18:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int v=0;v<G[x].size();v++) ~^~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:54:5: warning: this ‘for’ clause does not guard... [-Wmisleading-indentation] for(i=1;i<=n;i++) ^~~ user.cpp:57:9: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the ‘for’ if(!ok) ^~