// No333.cpp : Defines the entry point for the console application.
//
#include <assert.h>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <climits>
using namespace std;
typedef unsigned char uchar;
typedef unsigned int uint;
typedef long long ll;
typedef unsigned long long ull;

#define NMAX 2000000000

int main()
{
	int A, B;
	cin >> A >> B;
	int ans = 0;
	if (A > B) {
		ans = NMAX - B - 1;
	}
	else {
		ans += B - 2;
	}
	cout << ans << endl;
    return 0;
}