POJ 2509

#include <iostream>
#include <stdio.h>
using namespace std;

int main()
{
    //freopen("acm.acm","r",stdin);
    int n;
    int k;    
    int sum;
    int mod;
    int tem;
    while(cin>>n>>k)
    {
        sum = 0;
        while(n >= k)
        {
            mod = n % k;
            tem = n / k;
            sum += n - mod;
            n = mod + tem;
        }
        sum += mod + tem;
        cout<<sum<<endl;

    }
}