View Compilation Error

0_0_4273360_21999.cpp:1: error: `__int64' does not name a type
0_0_4273360_21999.cpp: In function `int main()':
0_0_4273360_21999.cpp:21: error: `f' undeclared (first use this function)
0_0_4273360_21999.cpp:21: error: (Each undeclared identifier is reported only once for each function it appears in.)