View Compilation Error

1002215_0_0_263.cpp: In function `int main()':
1002215_0_0_263.cpp:4: error: `_int64' undeclared (first use this function)
1002215_0_0_263.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
1002215_0_0_263.cpp:4: error: expected `;' before "sum"
1002215_0_0_263.cpp:5: error: expected `;' before "n"
1002215_0_0_263.cpp:6: error: `n' undeclared (first use this function)
1002215_0_0_263.cpp:8: error: `sum' undeclared (first use this function)