import java.io.*;
import java.util.*;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner scan = new Scanner(System.in);
		int evens = scan.nextInt();
		int odds = scan.nextInt();
		int sum = 0;
		sum += (evens * (evens - 1)) / 2;
		sum += (odds * (odds - 1)) / 2;
		System.out.println(sum);
	}

}

/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