View Compilation Error

0_0_36455293_29869.cpp:18:1: error: 'vector' does not name a type
 vector<int> v[maxn];
 ^
0_0_36455293_29869.cpp: In function 'void DFS(int, int)':
0_0_36455293_29869.cpp:50:16: error: 'v' was not declared in this scope
     for(auto f:v[m])
                ^
0_0_36455293_29869.cpp: In function 'void solve()':
0_0_36455293_29869.cpp:62:5: error: 'cin' was not declared in this scope
     cin >> n;
     ^
0_0_36455293_29869.cpp:66:9: error: 'v' was not declared in this scope
         v[i].push_back(t);
         ^
0_0_36455293_29869.cpp:82:9: error: 'cout' was not declared in this scope
         cout << ans1 << " " << ans2 << endl;
         ^
0_0_36455293_29869.cpp:82:40: error: 'endl' was not declared in this scope
         cout << ans1 << " " << ans2 << endl;
                                        ^
0_0_36455293_29869.cpp:86:9: error: 'v' was not declared in this scope
         v[i].clear();
         ^
0_0_36455293_29869.cpp: In function 'int main()':
0_0_36455293_29869.cpp:95:2: error: 'cin' was not declared in this scope
  cin.sync_with_stdio(0);
  ^