

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int m = scan.nextInt();

		int anser;

		if (n == 0) {
			anser = m * (m - 1) / 2;
		} else if (m == 0) {
			anser = n * (n - 1) / 2;
		} else {
			anser = (n * (n - 1) + m * (m - 1)) / 2;
		}

		System.out.println(anser);
	}

}

/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