View Compilation Error

0_0_13599304_26318.cpp: In function 'll bin(ll)':
0_0_13599304_26318.cpp:43:10: error: 'f' was not declared in this scope
       if(f[n]==a[i]) return n;
          ^
0_0_13599304_26318.cpp:44:10: error: 'f' was not declared in this scope
       if(f[1]==a[i]) return 1;
          ^
0_0_13599304_26318.cpp:48:16: error: 'f' was not declared in this scope
             if(f[mid]==a[i]) return mid;
                ^
0_0_13599304_26318.cpp:49:16: error: 'f' was not declared in this scope
             if(f[mid]<a[i]) l=mid;
                ^