#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
typedef long long ll;

int main(){
    int n , k;
    cin >> n >> k;
    
    if(k >= n){
        cout << n << endl;
        exit(0);
    }
    
    ll ans;
    if(n % 2 == 0){
        if(k % 2 == 0)ans = min(k + 1 , n / 2);
        else ans = min(k , n / 2);
    }else{
        if(k % 2 == 0)ans = min((k + 1) / 2 + (k + 1) / 2 + 1 , n);
        else ans = min((k + 1) / 2 + (k + 1) / 2 , n);
    }
    cout << ans << endl;
    return 0;
}