#如题

#include<iostream>
using namespace std;
int n,k;
int drink,num,t;
int main(){
	cin>>n>>k;
	num=n;
	drink=n/k;
	t=drink%k;
	while(drink>=1){
		num+=drink;
		drink=(drink+t)/k;//update new drink
		t=drink%k;
	}
	cout<<num;
	return 0;
}