#include <iostream>

using namespace std;

int main(int argc, char** argv)
{
	const unsigned int max = 2000000000;
	unsigned int a, b, c=0;
	cin >> a >> b;

	if (a < b) {
		c = (b-a + a-1);
		c += (a!=1) * -1;
		c += (b==max) * -1;
		cout << c << endl;
	}
	else {
		cout << (max-b-1) << endl;
	}

	return 0;
}