View Compilation Error

769995_0_0_28666.cpp: In function `int main()':
769995_0_0_28666.cpp:6: error: `_int64' undeclared (first use this function)
769995_0_0_28666.cpp:6: error: (Each undeclared identifier is reported only once for each function it appears in.)
769995_0_0_28666.cpp:6: error: expected `;' before "sum"
769995_0_0_28666.cpp:9: error: `sum' undeclared (first use this function)