#include <bits/stdc++.h>

 using namespace std;

 typedef long long ll;

 const ll INF = 0x3f3f3f3f3f3f3f3f;

 ll cal(ll x, ll y, ll i, ll & minn, ll & ans)

 {

     if (i > x)

     {

         if (y + i - x < minn)

         {

             minn = y + i - x;

             ans = i - x;

         }

     }

     else

     {

         ll k = ;

         if (x % i) k = (x / i + ) * i - x;

         ll t = (x + k) * (y + k) / __gcd(y - x, x + k);

         if (t < minn)

         {

             minn = t;

             ans = k;

         }

     }

 }

 int main()

 {

     ll a, b;

     while (cin >> a >> b)

     {

         ll x = min(a, b), y = max(a, b);

         if (y % x == ) { cout <<  << endl; continue; }

         ll minn = INF, ans = ;

         for (int i = ; i * i <= y - x; i++)

         {

             if ((y - x) % i == )

             {

                 cal(x, y, i, minn, ans);

                 if ((y - x) / i != i) cal(x, y, (y - x) / i, minn, ans);

             }

         }

         cout << ans << endl;

     }

     return ;

 }