View Compilation Error

0_0_17012981_5442.cpp: In function 'int main()':
0_0_17012981_5442.cpp:6:5: error: '_int64' was not declared in this scope
     _int64 sum;
     ^
0_0_17012981_5442.cpp:11:9: error: 'sum' was not declared in this scope
         sum=0;
         ^