View Compilation Error

0_0_7851443_27596.cpp:6: error: `main' must return `int'
0_0_7851443_27596.cpp: In function `int main(...)':
0_0_7851443_27596.cpp:9: error: `_int64' undeclared (first use this function)
0_0_7851443_27596.cpp:9: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_7851443_27596.cpp:9: error: expected `;' before "sum"
0_0_7851443_27596.cpp:32: error: `sum' undeclared (first use this function)