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

//#include<bits/stdc++.h>



using namespace std;

int gcd(int x,int y){
	return y?gcd(y,x%y):x;
}


int main(){
	int n,d;
	cin>>n>>d;
	cout<<n/gcd(n,d)-1<<endl;
	return 0;
	

}