View Compilation Error

0_0_39098429_32684.cpp:5:17: error: '_int64' has not been declared
    5 | int haha(int a, _int64 b)
      |                 ^~~~~~
0_0_39098429_32684.cpp: In function 'int main()':
0_0_39098429_32684.cpp:26:1: error: '_int64' was not declared in this scope
   26 | _int64 n;
      | ^~~~~~
0_0_39098429_32684.cpp:35:17: error: 'n' was not declared in this scope
   35 | scanf("%I64d", &n);
      |                 ^