#include<stdio.h>
int isti(int n)
{   return n;
}

int kvadrat(int n)
{   return n*n;
}

int suma(int (*f) (int),int n)
{   int i, suma=0;
    for (i=0; i<=n; i++)
       suma+=(*f)(i);
    return suma;
} 

int main()
{  printf("%d\n",suma(isti,3));
   printf("%d\n",suma(kvadrat,5));
   return 0;
}