#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);
}
int main() {
    ll a,b;cin>>a>>b;
    ll a1=a;
    ++a;++b;
    ll ans=1;
    ll maxn=a*b/gcd(a,b);
    for(;a<=2*a1;++a,++b)
    {
        ll temp=a/gcd(a,b)*b;
        if(temp<maxn)
        {
            maxn=temp;
            ans=a-a1;
        }
    }
    cout<<ans<<'\n';
}