#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <ostream>
#include <queue>
#include <stack>
#include <string>
#include <vector>
#define INF 10000000
#define rep(i,n) for (int i=0;i<(n);i++)
#define rev(i,n) for (int i=(n)-1;i>=0;i--)
using namespace std;
typedef long long ll;
typedef pair<int, int> p;
typedef queue<int> qi;
typedef queue< pair<int, int> > qp;
typedef vector<int> vi;
typedef vector<int, int> vii;
typedef vector<string> vs;
typedef vector< pair<int, int> > vp;
int dx[4] = { 0, 1, 0, -1 };
int dy[4] = { 1, 0, -1, 0 };

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

  ll a,b;
  cin >> a >> b;

  if(a > b) cout << 2000000000  - b - 1 << endl;
  else cout << b - 2 << endl;

	return 0;
}