View Compilation Error

26908_0_31351.cpp: In function `int main()':
26908_0_31351.cpp:6: error: `_int64' undeclared (first use this function)
26908_0_31351.cpp:6: error: (Each undeclared identifier is reported only once for each function it appears in.)
26908_0_31351.cpp:6: error: expected `;' before "sum"
26908_0_31351.cpp:11: error: `sum' undeclared (first use this function)