#include<stdio.h>

long r, d, c, contor;

void citire()
{
  freopen("pascal.in","r",stdin);
  freopen("pascal.out","w",stdout);
  scanf ("%ld %ld",&r,&d);
}

int main()
{
  citire();
  long i, a,b, x;
  for (c=2; c<r; c++)
    {
      i=d;
      contor=0;
      while ((c/i)!=0) {contor+=(c/i); i*=d;}
      a=contor;

      contor=0;
      while ((r/i)!=0) {contor+=(r/i); i*=d;}
      b=contor;

      contor=0;
      while ((r-c)/i!=0) {contor+=((r-c)/i); i*=d;}
      x=contor;
       
      b=b-x-a;
      contor=b;
    }
  printf("%ld",contor);
  return 0;
}