View Compilation Error

0_0_31794136_20314.cpp: In function 'int main()':
0_0_31794136_20314.cpp:10:7: error: redeclaration of 'int i'
   int i;
       ^
0_0_31794136_20314.cpp:6:10: note: 'int i' previously declared here
  for(int i=0;i<n;i++)
          ^
0_0_31794136_20314.cpp:13:20: error: 'f' was not declared in this scope
    if(((a-1)/6==f(i))&&(a-1)%6==0)
                    ^