#include <iostream>
#include <cstdlib>
using namespace std;
long long a, b, c, sol, N;

long long Euclid(long long A, long long B)
{
	long long r;
	while(B)
	{
		r = A % B;
		A = B;
		B = r;
	}
	return A;
}

int main()
{
	int i, now;
	cin >> a >> b;
	c = Euclid(a, b);
	N = 1;
	sol = 200000000000000000LL;
	for(i = 1; i * i <= c; ++i)
	{
		now = Euclid(a + i, b + i);
		if(((a + i) * (b + i)) / now < sol || (((a + i) * (b + i)) / now == sol && N > i))
		{
			sol = ((a + i) * (b + i)) / now;
			N = i;
		}
		if(c % i == 0)
		{
			now = Euclid(a + c / i, b + c / i);
			if(((a + c / i) * (b + c / i)) / now < sol || (((a + c / i) * (b + c / i)) / now == sol && N > c / i))
			{
				sol = ((a + c / i) * (b + c / i)) / now;
				N = c / i;
			}
		}
	}
	c = abs(a - b);
	for(i = 1; i * i <= c; ++i)
	{
		now = Euclid(a + i, b + i);
		if(((a + i) * (b + i)) / now < sol || (((a + i) * (b + i)) / now == sol && N > i))
		{
			sol = ((a + i) * (b + i)) / now;
			N = i;
		}
		if(c % i == 0)
		{
			now = Euclid(a + c / i, b + c / i);
			if(((a + c / i) * (b + c / i)) / now < sol || (((a + c / i) * (b + c / i)) / now == sol && N > c / i))
			{
				sol = ((a + c / i) * (b + c / i)) / now;
				N = c / i;
			}
		}
	}
	for(i = 1; i <= 300000; ++i)
	{
		now = Euclid(a + i, b + i);
		if(((a + i) * (b + i)) / now < sol || (((a + i) * (b + i)) / now == sol && N > i))
		{
			sol = ((a + i) * (b + i)) / now;
			N = i;
		}
	}
	cout << N << "\n";
	return 0;
}