#include <iostream>

using namespace std;

int main(){
	int n=0,k=0,p=0,y=0;
	cin>>n>>k;
	y=n;
	for(;y>=k;){		
		p+=n;
		n=y/k;			//换烟
		y-=y/k; 
		y+=n;			//吸烟 
		if(y<k){
			break;
		}
	}
	cout<<p;
	return 0;
}