View Compilation Error

0_0_2724870_10912.cpp:15: error: `_int64' does not name a type
0_0_2724870_10912.cpp: In function `int main()':
0_0_2724870_10912.cpp:20: error: `num' undeclared (first use this function)
0_0_2724870_10912.cpp:20: error: (Each undeclared identifier is reported only once for each function it appears in.)