View Compilation Error

1073650_0_0_15370.cpp: In function `int main()':
1073650_0_0_15370.cpp:4: error: `_int64' undeclared (first use this function)
1073650_0_0_15370.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
1073650_0_0_15370.cpp:4: error: expected `;' before "sum"
1073650_0_0_15370.cpp:5: error: expected `;' before "n"
1073650_0_0_15370.cpp:6: error: `n' undeclared (first use this function)
1073650_0_0_15370.cpp:8: error: `sum' undeclared (first use this function)