#include <bits/stdc++.h> 

using namespace std;
using ll=long long;
using ull=unsigned long long;
using pii=pair<int,int>;

#define INF LONG_MAX
#define MOD1 1000000007
#define MOD2 998244353
#define MOD MOD1
#define rng(a) a.begin(),a.end()
#define rrng(a) a.end(),a.begin()
#define endl "\n"
#define int ll

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);

    int N,K,M;
    cin>>N>>K>>M;
    int ans=0;
    int d=1;
    if(N<=M){
        cout<<0<<endl;
        return 0;
    }
    while(true){
        int nd=N/d;
        int nkd=(N-K)/d;
        int kd=K/d;
        ans+=nd-nkd-kd;
        if(d>N/M){
            break;
        }
        d*=M;
    }
    cout<<ans<<endl;

    return 0;
}