#include <iostream>
using namespace std;


int main()
{
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    freopen("errors.txt", "w", stderr);
#endif
    double n ; int k ;
    cin >> n >> k ;
    if(n <= k) {
        cout << n ; return 0 ;
    }
    int i = n * (1 - (1.0/k)) ;
    bool flag =1 ;
    int v=0 ;
    while(flag) {
        int p =0 ;
        double x = 1 ;
        double sum =0 ;
        while(i >= x) {
            sum += (i / x) ;
            if(sum >= n) {
                v = i ;
                flag =0 ;
            }
            x *= k ;
        }
        i++;
    }
    cout << v ;
}