#include <iostream>
#include <fstream>
using namespace std;
ifstream si("pascal.in");
ofstream so("pascal.out");
int main()
{
    int n,k;
    si>>n>>k;
    int put=1;
    int sum=0;
    n++;
    while(put<=n)
    {
        put*=k;
    }
    put/=k;
    //    cout<<put;
    while(put)
    {
        int niv=n%put;
        if(niv==0)
            niv=put;
        niv=put-niv;
        sum+=(n/put)*niv;
        n%=put;
        put/=k;
    }
    so<<sum<<'\n';
    return 0;
}