#include<bits/stdc++.h>
#define rep(i,n) for(int i=0; i< (n); i++)
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
const int mod = 998244353;
const int inf = (1<<30);
const ll INF = (1ull<<62);

ll f(ll n,ll k){
    ll ans = 0;
    while(n > 0){
        ans += n/k;
        n /= k;
    }
    return ans;
}

int main(){
    ll n,k,m; cin>>n>>k>>m;
    ll t = n-k;
    cout<<f(n,m) - f(k,m) - f(t,m)<<endl;    
}