lcm-gcd

#include <iostream>
#include <iomanip>
#include <vector>
#include <string>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <set>

using namespace std;


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

int main()
{
    int x, y;
    cin >> x >> y;
    if (x == y)
    {
        cout << 0 << endl;
        return 0;
    }

    if (x > y)
        swap(x, y);
    long long g = gcd(x, y);
    long long l = x / g;
    l *= y;

    cout << l - g << endl;

    return 0;
}