what's wrong?
#include <stdio.h>
#include <conio.h>

main()
{
      int a,len=0,t=1;
      char b[20];
      scanf("%d%s",&a,b);
      len = strlen(b);
      for( ; a > 1 ; a -= len )
           t *= a;
      printf("%d",t);
      return 0;
}

int result = 1;

for (int i = n; i > 0; i -= k)
  result *= i;

printf("%d\n", result);