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

int64_t count(int64_t n, int64_t p)
{
    if (n == 0)
    {
        return 0;
    }
    return n / p + count(n / p, p);
}

int main()
{
    int64_t n, k, m;
    cin >> n >> k >> m;
    cout << count(n, m) - count(k, m) - count(n - k, m) << endl;
    return 0;
}