#include <iostream>
#include <algorithm>


using namespace std;

int main() {
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);

    unsigned long long n, k;
    cin >> n >> k;
    if (n>=k) {
        cout << k-1;
        return 0;
    }
    else cout <<2*n-k+1;

    return 0;
}