View Compilation Error

533992_0_0_7336.cpp: In function `int main()':
533992_0_0_7336.cpp:5: error: `_int64' undeclared (first use this function)
533992_0_0_7336.cpp:5: error: (Each undeclared identifier is reported only once for each function it appears in.)
533992_0_0_7336.cpp:5: error: expected `;' before "sum"
533992_0_0_7336.cpp:8: error: `sum' undeclared (first use this function)