#include <iostream>

using std::cin;
using std::cout;
using std::endl;


long long a, b;

long long gcd(long long a, long long b) {
	return b == 0 ? a : gcd(b, a % b);
}

long long solve() {
	for (long long i = b;i >= a;i--)
		for (long long j = a;j <= b;j++)
			if (gcd(a, b) == 1) {
				return b - a + 1;
			}
}

int main() {
	cin >> a >> b;
	long long max;
	cout << solve();
//	cin >> a;
}