#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(v) v.begin(),v.end()
typedef long long ll;
 
#include<bits/stdc++.h>
using namespace std;
 
int main(){
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  
  ll n,k,m;
  cin>>n>>k>>m;
  
  ll ans=0;
  ll t=m;
  while(n/t>=1){
    ans+=n/t;
    if(t>n/m) break;
    t*=m;
  }
  t=m;
  while(k/t>=1){
    ans-=k/t;
    if(t>k/m) break;
    t*=m;
  }
  t=m;
  while((n-k)/t>=1){
    ans-=(n-k)/t;
    if(t>(n-k)/m) break;
    t*=m;
  }
  cout<<ans<<endl;
  
  return 0;
}