View Compilation Error

0_0_7297783_4891.cpp:2: error: `_int64' does not name a type
0_0_7297783_4891.cpp: In function `int main()':
0_0_7297783_4891.cpp:8: error: `a' undeclared (first use this function)
0_0_7297783_4891.cpp:8: error: (Each undeclared identifier is reported only once for each function it appears in.)