View Compilation Error

0_0_15912138_22629.cpp:4:1: error: '_int64' does not name a type
 _int64 Fib(int n)
 ^
0_0_15912138_22629.cpp: In function 'void run()':
0_0_15912138_22629.cpp:20:26: error: 'Fib' was not declared in this scope
  printf("%I64d\n",Fib(m-n));
                          ^