View Compilation Error

0_0_19940723_17154.cpp: In function 'int main()':
0_0_19940723_17154.cpp:34:13: error: 'f' was not declared in this scope
             f[i]=f[q[head]]+(sum[i]-sum[q[head]])*(sum[i]-sum[q[head]])+m;  
             ^
0_0_19940723_17154.cpp:38:15: error: 'f' was not declared in this scope
         cout<<f[n]<<endl;
               ^