#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

int main() {
    int n, k;
    cin >> n >> k;

    if (n % 2 == 0) {
        cout << min(k + 1, n / 2) << endl;
    } else {
        cout << min(k + 1, n) << endl;
    }

    return 0;
}