View Compilation Error

0_0_23643798_27335.cpp: In function 'int main()':
0_0_23643798_27335.cpp:6:2: error: '_int64' was not declared in this scope
  _int64 sum;
  ^
0_0_23643798_27335.cpp:9:3: error: 'sum' was not declared in this scope
   sum = 3;
   ^