#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <stdio.h>
#include <cstring>
#include <queue>
#include <stack>
#include <functional>
#include <math.h>
using namespace std;
#define Would
#define you

int main() {
	long long a, b, ans;
	cin >> a >> b;
	if (a > b) {
		ans = 2000000000 - 1 - b;
	}
	else {
		ans = b - 2;
	}
	cout << ans << endl;
}