View Compilation Error

0_0_34066413_50.cpp:4:9: error: '_int64' does not name a type
 typedef _int64 ll;
         ^
0_0_34066413_50.cpp:5:1: error: 'll' does not name a type
 ll C(ll a, ll b) {
 ^
0_0_34066413_50.cpp: In function 'int main()':
0_0_34066413_50.cpp:18:2: error: 'll' was not declared in this scope
  ll n;
  ^
0_0_34066413_50.cpp:19:16: error: 'n' was not declared in this scope
  while (cin >> n) {
                ^
0_0_34066413_50.cpp:20:6: error: expected ';' before 'res'
   ll res = 0;
      ^
0_0_34066413_50.cpp:21:11: error: expected ';' before 'i'
   for (ll i = 2; i <= n; i++) {
           ^
0_0_34066413_50.cpp:21:18: error: 'i' was not declared in this scope
   for (ll i = 2; i <= n; i++) {
                  ^
0_0_34066413_50.cpp:23:4: error: 'res' was not declared in this scope
    res += (ll)(i - 1) * C(n, i);
    ^
0_0_34066413_50.cpp:23:31: error: 'C' was not declared in this scope
    res += (ll)(i - 1) * C(n, i);
                               ^
0_0_34066413_50.cpp:26:11: error: 'res' was not declared in this scope
   cout << res << endl;
           ^