P1150

#include<bits/stdc++.h>

using namespace std;
int n,k;
int ans=0,ank=0;

int main(){
	cin >> n >> k;
	for (int i=1;i<n;i++){
        
			
			                if (i%k==0)
			                    ans++;
		for (int j=1;j<n;j++){
			 if (ans%k==0)
				ans++;		                   
			else			         
			    break;				           
			
		}
			               
		
                
	}
	cout << ans+n-1;
	return 0;
}