#include <iostream>
using namespace std;

typedef long long ll;

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

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

int main() {
    ll n, d;
    cin >> n >> d;

    ll l = lcm(n, d);
    cout << l / d - 1 << endl;
    return 0;
}