using namespace std;

#include <iostream>
#include <vector>
#include <utility>
#include <algorithm>

int main(){
    long long H, A;

    cin >> H >> A;

    long long attack_count = 0;

    long long hp = H;

    while (hp > 0){
        hp = hp / A;
        attack_count++;
    }

    long long ans = 0;
    long long need_attack = 1;

    for (int i = 0; i < attack_count; i++){
        ans += need_attack;
        need_attack *= 2;
    }

    cout << ans << endl;
}