View Compilation Error

0_0_37185788_30767.cpp:5:1: error: 'vector' does not name a type
 vector<int>G[N];
 ^
0_0_37185788_30767.cpp: In function 'void dfs(int, int)':
0_0_37185788_30767.cpp:15:12: error: 'G' was not declared in this scope
  for(int v:G[u])
            ^
0_0_37185788_30767.cpp: In function 'int main()':
0_0_37185788_30767.cpp:29:8: error: 'cin' was not declared in this scope
  while(cin>>n)
        ^
0_0_37185788_30767.cpp:34:22: error: 'scanf' was not declared in this scope
    scanf("%d%d",&u,&v);
                      ^
0_0_37185788_30767.cpp:35:4: error: 'G' was not declared in this scope
    G[u].push_back(v);
    ^
0_0_37185788_30767.cpp:42:22: error: 'printf' was not declared in this scope
   printf("%lld\n",ans);
                      ^