View Compilation Error

0_0_26253004_22742.cpp:4:1: error: '_int64' does not name a type
 _int64 result(int n)
 ^
0_0_26253004_22742.cpp: In function 'int main()':
0_0_26253004_22742.cpp:21:35: error: 'result' was not declared in this scope
         printf("%I64d\n", result(n));
                                   ^