View Compilation Error

0_0_39016060_31177.cpp: In function 'int main()':
0_0_39016060_31177.cpp:8:5: error: '_int64' was not declared in this scope
    8 |     _int64 a[25],b[25],ans;
      |     ^~~~~~
0_0_39016060_31177.cpp:9:5: error: 'a' was not declared in this scope
    9 |     a[0] = 1;a[1]=1,a[2] = 2;
      |     ^
0_0_39016060_31177.cpp:12:9: error: 'b' was not declared in this scope
   12 |         b[2] = 1,b[3] =2;
      |         ^
0_0_39016060_31177.cpp:19:9: error: 'ans' was not declared in this scope; did you mean 'abs'?
   19 |         ans=a[n]/a[m]/a[n-m]*b[m];
      |         ^~~
      |         abs