View Compilation Error

0_0_15725124_8113.cpp: In function 'int main()':
0_0_15725124_8113.cpp:5:2: error: '_int64' was not declared in this scope
  _int64 f[50]={1,1};
  ^
0_0_15725124_8113.cpp:6:19: error: 'f' was not declared in this scope
  for(i=2;i<50;i++)f[i]=f[i-1]+f[i-2];
                   ^
0_0_15725124_8113.cpp:11:25: error: 'f' was not declared in this scope
         printf("%lld\n",f[b-a]);
                         ^