#include<iostream.h>
int main()
{int n, k=0;
int result = 1;
char test[20];
scanf("%d %s",&n, test);

while (test[k++]);
k--;

while (n>0)
   { result *= n;
     n = n-k;
   }

printf("%d", result);

        return 0;
}
What is wrong?!

#include<stdio.h>