View Compilation Error

0_0_39305075_1317.cpp:12:1: error: '_int64' does not name a type
   12 | _int64 c(int a, int b)
      | ^~~~~~
0_0_39305075_1317.cpp: In function 'int main()':
0_0_39305075_1317.cpp:26:9: error: '_int64' was not declared in this scope
   26 |         _int64 s[15], sum;
      |         ^~~~~~
0_0_39305075_1317.cpp:27:9: error: 's' was not declared in this scope
   27 |         s[1] = 0; s[2] = 1;
      |         ^
0_0_39305075_1317.cpp:36:17: error: 'sum' was not declared in this scope
   36 |                 sum = 1;
      |                 ^~~
0_0_39305075_1317.cpp:39:32: error: 'c' was not declared in this scope
   39 |                         sum += c(i, n) * s[i];
      |                                ^