#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr char newl = '\n';

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

    int n, k;
    cin >> n >> k;

    if (n & 1) {
        cout << min(n, k + 1) << newl;
    } else {
        cout << min(n / 2, k + 1) << newl;
    }

    return 0;
}