View Compilation Error

0_0_17312038_16840.cpp: In function 'int main()':
0_0_17312038_16840.cpp:9:2: error: '_int64' was not declared in this scope
  _int64 sum;
  ^
0_0_17312038_16840.cpp:13:3: error: 'sum' was not declared in this scope
   sum = 0;
   ^