View Compilation Error

0_0_38863515_1509.cpp:2:1: error: '_int64' does not name a type
    2 | _int64 num(int m, int N)
      | ^~~~~~
0_0_38863515_1509.cpp: In function 'int main()':
0_0_38863515_1509.cpp:13:9: error: '_int64' was not declared in this scope
   13 |         _int64 a;
      |         ^~~~~~
0_0_38863515_1509.cpp:21:25: error: 'a' was not declared in this scope
   21 |                         a = num(m,N);
      |                         ^
0_0_38863515_1509.cpp:21:29: error: 'num' was not declared in this scope; did you mean 'enum'?
   21 |                         a = num(m,N);
      |                             ^~~
      |                             enum