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

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long N = in.nextLong();
        long M = in.nextLong();
        long x=N-1;
        long y=M-1;
        long y_cut = 1;
        long x_cut = 1;
        long cut=0;
        while(x>0 && y>0){
            if(x>y){
                x--;
                x_cut++;
                cut += y_cut;
            }else{
                y--;
                y_cut++;
                cut += x_cut;
            }
        }
        cut =cut+ x*y_cut + y*x_cut;
        System.out.println(cut);
    }
}