백준 #25628번 햄버거 만들기

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		
		int a = sc.nextInt();
		int b = sc.nextInt();
		
		a = a / 2;
		
		if(a >= b) {
			System.out.println(b);
		}else {
			System.out.println(a);
		}
		sc.close();
	}
}