#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll n,k,ans;
int a[1000000];
int main()
{
    freopen("Gold_coin.in","r",stdin);
    freopen("Gold_coin.out","w",stdout);
    ios::sync_with_stdio(false);
    cin.tie(nullptr);cout.tie(nullptr);
    cin>>n>>k;
    if(n<=k) cout<<n<<'\n'; 
    else
    {
        ans=k;
        while(true)
        {
            ll tmp=ans;
            ll tmp1=tmp/(k-1);
            if(tmp%(k-1)) tmp1++;
            ll tmp2=tmp1*(k-1)-tmp;
            ll tmp3=k*tmp1-tmp2;
            if(tmp3>n)
            {
                cout<<ans<<'\n';
                break;
            }
            else ans=tmp3;
        }
    }
    return 0;
}