#include <cassert>
#include <iostream>
using namespace std;
using ll = long long;

int main() {
    ll H, A;
    cin >> H >> A;
    assert(1 <= H && H <= 1000000000000);
    assert(2 <= A && A <= 1000000000000);
    ll ans = 0;
    ll cnt = 1;
    while (H > 0) {
        H /= A;
        ans += cnt;
        cnt *= 2;
    }
    cout << ans << endl;
    return 0;
}