#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <string.h>
#include <vector>
using namespace std;

#define ll long long
#define INF (1 << 30)
#define INFLL (1LL << 60)

#define FOR(i,a,b) for(ll i = (a);i<(b);i++)
#define REP(i,a) FOR(i,0,(a))
#define MP make_pair

ll gcd(int a, int b){
	int r;
	while((r = a % b) != 0){
		a = b;
		b = r;
	}
	return b;
}

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

int main() {
	ll n, d;
	cin >> n >> d;
	ll ret = lcm(n, d);
	cout << ret / d - 1 << endl;
	return 0;
}