import java.util.Scanner;


public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(); //偶数球
        int m = sc.nextInt(); //奇数球
        System.out.println(choose(n, 2) + choose(m, 2));

    }

    static int choose (int n, int k){
        int ret = 1;
        if(n == k) {
            return 1;
        }else {
            for(int i = 0; i < k; i++){
                ret = ret * (n-i) / (i + 1);
            }
        return ret;}
    }
}
/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