#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>
//#include<bits/stdc++.h>


using namespace std;

int main(){
	long long int a,b;
	cin>>a>>b;
	while(1){
		long long int t=a/b;
		t/=b;
		a-=t;
		b--;
		if(b==1)break;
		//cout<<a;
	}
	cout<<a<<endl;

	return 0;
}