View Compilation Error

785226_0_0_16789.cpp: In function `int main()':
785226_0_0_16789.cpp:9: error: `_int64' undeclared (first use this function)
785226_0_0_16789.cpp:9: error: (Each undeclared identifier is reported only once for each function it appears in.)
785226_0_0_16789.cpp:9: error: expected `;' before "sum"
785226_0_0_16789.cpp:10: error: `num' undeclared (first use this function)
785226_0_0_16789.cpp:11: error: `sum' undeclared (first use this function)