import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    public static long mincut(int n, int m){
        long res = 0;
        if(n==1){
            return m-1;
        }
        else if(m==1){
            return n-1;
        }
        int max = Math.max(n, m);
        int min = Math.min(n, m);
        if(max%2==0)
            res = 1 + 2*mincut(min, max/2);
        else
            res = 1 + mincut(min, max/2) + mincut(min, 1+max/2);
        return res;
    }
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int m = in.nextInt();
        System.out.println(mincut(n,m));
    }
}