#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    // [N!] / [K! (N-K)!]
    ll N,K,M; cin >> N >> K >> M;
    auto f = [M](ll X) {
        ll res = 0, m = M;
        do {
            res += X / m;
            m *= M;
        } while(2 <= m && m <= X);
        return res;
    };

    ll x = f(N) - (f(K) + f(N - K));
    cout << x << endl;
}