#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <string>
#include <sstream>
#include <cmath>
#include <stack>
#include <cctype>
#include <stdio.h>
#include <map>
#include <string.h>

typedef long long ll;

using namespace std;

long long  gcd(long long a, long long b){
	if(b==0){
		return a;
	}
	return gcd(b, a%b);
}

long long lcm(long long a, long long b){
	return a/gcd(a,b)*b;
}

int main() {

	ll n,d ;
	cin>>n>>d;

	cout<<lcm(n,d)/d-1<<endl;


	return 0;
}