#include<iostream>
#include<vector>
#include<cassert>
#include<string>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<cmath>
#include<stack>
#include<queue>
#include<set>
#include<map>
#include<tuple>
using namespace std;

typedef pair<int,int> pii;
typedef long long ll;
typedef ll int__;
#define rep(i,j) for(int__ i=0;i<(int__)(j);i++)
#define repeat(i,j,k) for(int__ i=(j);i<(int__)(k);i++)
#define all(v) v.begin(),v.end()

const int MAX_C = 2000000000;

bool solve(){
    int A,B; cin >> A >> B;
    if(A > B){
        // => C > B and C != A
        cout << MAX_C - B -1 << endl;
    }
    else if( A < B){
        // => C < B and C != A
        cout << B - 2 << endl;
    }
    return false;
}

int main()
{
    ios::sync_with_stdio(false);
    while(solve());
    return 0;
}