View Compilation Error

287266_0_10322.cpp: In function `int main()':
287266_0_10322.cpp:7: error: `_int64' undeclared (first use this function)
287266_0_10322.cpp:7: error: (Each undeclared identifier is reported only once for each function it appears in.)
287266_0_10322.cpp:7: error: expected `;' before "n"
287266_0_10322.cpp:8: error: `n' undeclared (first use this function)
287266_0_10322.cpp:12: error: `sum' undeclared (first use this function)