adun

#include <iostream>
using namespace std;

int main()
{
    long long x,y;
    cin>>x>>y;
    if(x>y)
        swap(x,y);
    if(2*x>y)
        cout<<(x/(y-x)+1)*(y-x)-x;
    else
    {
        long long dif=y-x;
        long long k=dif/x;
        for(;k&&dif%k;--k);
        cout<<dif/k-x;
    }
}