#include<iostream>
#include<vector>
using namespace std;
int main()
{
    int n,k,res=0;
    cin>>n>>k;
    vector<int>a(n,1);
    for (int i=0;i<a.size();i++)
    {
        a[i]=0;
        res++;
        if ((i+1)%k==0)
            a.push_back(1);
        
    }
    cout<<res;
    return 0;
}