import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {

		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		String[] str = reader.readLine().split(" ");
		int N = Integer.parseInt(str[0]);
		int K = Integer.parseInt(str[1]);
		if (N % 2 == 1) {
			int ans = Math.min(N, 1+K);
			System.out.println(ans);
		}
		else {
			int ans = Math.min(N/2, 1+K);
			System.out.println(ans);
		}


	}
}