View Compilation Error

0_0_20833608_16999.cpp:3:1: error: '_Longlong' does not name a type
 _Longlong gcd(_Longlong x, _Longlong y)
 ^
0_0_20833608_16999.cpp:17:1: error: '_Longlong' does not name a type
 _Longlong work(_Longlong x, _Longlong y)
 ^
0_0_20833608_16999.cpp: In function 'int main()':
0_0_20833608_16999.cpp:23:2: error: '_Longlong' was not declared in this scope
  _Longlong n, a;
  ^
0_0_20833608_16999.cpp:24:16: error: 'n' was not declared in this scope
  while (cin >> n >> a && (n || a))
                ^
0_0_20833608_16999.cpp:24:21: error: 'a' was not declared in this scope
  while (cin >> n >> a && (n || a))
                     ^
0_0_20833608_16999.cpp:26:13: error: expected ';' before 'u'
   _Longlong u, v;
             ^
0_0_20833608_16999.cpp:27:10: error: 'u' was not declared in this scope
   cin >> u;
          ^
0_0_20833608_16999.cpp:30:11: error: 'v' was not declared in this scope
    cin >> v;
           ^
0_0_20833608_16999.cpp:31:17: error: 'work' was not declared in this scope
    u = work(u, v);
                 ^