#include <iostream>

using namespace std;

int main(int argc, char** argv)
{
	const unsigned int max = 2000000000;
	unsigned int a, b;
	cin >> a >> b;

	if (a < b) {
		cout << (b-a) << endl;
	}
	else {
		cout << (max-b-1) << endl;
	}

	return 0;
}