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();
        int diff = Math.abs(a - b);
        int ans = (diff % 2 == 0) ? diff / 2 : diff / 2 + 1;
        System.out.println(ans);
        sc.close();
    }
}