View Compilation Error

217581_0_30160.cpp: In function `int main()':
217581_0_30160.cpp:4: error: `_int64' undeclared (first use this function)
217581_0_30160.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
217581_0_30160.cpp:4: error: expected `;' before "n"
217581_0_30160.cpp:5: error: `n' undeclared (first use this function)
217581_0_30160.cpp:29: error: `sum' undeclared (first use this function)