View Compilation Error

0_0_2081256_11007.cpp:5: error: `_int64' does not name a type
0_0_2081256_11007.cpp: In function `int main()':
0_0_2081256_11007.cpp:13: error: `a' undeclared (first use this function)
0_0_2081256_11007.cpp:13: error: (Each undeclared identifier is reported only once for each function it appears in.)