View Compilation Error

0_0_2869161_14181.cpp:4: error: `_int64' does not name a type
0_0_2869161_14181.cpp: In function `int main()':
0_0_2869161_14181.cpp:10: error: `sum' undeclared (first use this function)
0_0_2869161_14181.cpp:10: error: (Each undeclared identifier is reported only once for each function it appears in.)