import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int [] nums = new int[n+m];
        int i = 0;
        while (i<n){
            nums[i] = 2;
            i++;
        }
        while (i<n+m){
            nums[i] = 1;
            i++;
        }
        int count = 0;
        for(int j = 0; j<nums.length; j++){
            for(int k = j+1; k<nums.length; k++){
                if((nums[j]+nums[k])%2 == 0){
                    count++;
                }
            }
        }
        System.out.println(count);
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz