#include<iostream>
#include<string>
#include<algorithm>
#include<cmath>
#include<iomanip>
#include<cstring>
#include<map>
#include<vector>
#include<queue>
using namespace std;
typedef long long int ll;

int main(){

	ll a, b;
	cin >> a >> b;
	if(a>b){
		cout << 2000000000-b-1 << endl;
	} else {
		cout << b-2 << endl;
	}
  
  return 0;
}