View Compilation Error

0_0_32649176_18358.cpp:3:1: error: '_int64' does not name a type
 _int64 f(_int64 a)
 ^
0_0_32649176_18358.cpp: In function 'int main()':
0_0_32649176_18358.cpp:13:2: error: '_int64' was not declared in this scope
  _int64 n;
  ^
0_0_32649176_18358.cpp:14:16: error: 'n' was not declared in this scope
  while (cin >> n, n != -1)
                ^
0_0_32649176_18358.cpp:16:14: error: 'f' was not declared in this scope
   cout << f(n) << endl;
              ^