#include<bits/stdc++.h>
using namespace std;

int main() {
    long long N,K,M;
    cin >> N >> K >> M;
    long long tmp = M,sum1 = 0,sum2 = 0;
    while (true) {
        sum1 += N/tmp-(N-K)/tmp;
        sum2 += K/tmp;
        if(1001001001001001001/M > tmp) {
            tmp *= M;
        }
        else {
            break;
        }
    }
    cout << sum1-sum2 << endl;
}