#include <bits/stdc++.h>
using namespace std;
#define overload4(_1, _2, _3, _4, name, ...) name
#define rep1(n) for(int i = 0; i < (int)(n); ++i)
#define rep2(i, n) for(int i = 0; i < (int)(n); ++i)
#define rep3(i, a, b) for(int i = (a); i < (int)(b); ++i)
#define rep4(i, a, b, c) for(int i = (a); i < (int)(b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using u16 = uint16_t;
int main(){
    ull H, A;
    cin >> H >> A;
    int n = 0;
    while(H > 0){
        H /= A;
        ++n;
    }
    ull ans = 0;
    int i = 1;
    while(n > 0){
        ans += i;
        i *= 2;
        --n;
    }
    cout << ans << endl;
}