View Compilation Error

28819_0_10003.cpp: In function `int main()':
28819_0_10003.cpp:13: error: `_int64' undeclared (first use this function)
28819_0_10003.cpp:13: error: (Each undeclared identifier is reported only once for each function it appears in.)
28819_0_10003.cpp:13: error: expected `;' before "sum"
28819_0_10003.cpp:18: error: `sum' undeclared (first use this function)