View Compilation Error

397131_0_0_17475.cpp: In function `int main()':
397131_0_0_17475.cpp:3: error: `_int64' undeclared (first use this function)
397131_0_0_17475.cpp:3: error: (Each undeclared identifier is reported only once for each function it appears in.)
397131_0_0_17475.cpp:3: error: expected `;' before "num"
397131_0_0_17475.cpp:4: error: `num' undeclared (first use this function)
397131_0_0_17475.cpp:5: error: `a' undeclared (first use this function)