import java.util.Scanner;

public class Main {
	public static void main (String[] args) {
		int N;
		int M;
		Scanner scan = new Scanner(System.in);
		String num = scan.nextLine();
		String[] numbers = num.split(" ");
		N = Integer.parseInt(numbers[0]);
		M = Integer.parseInt(numbers[1]);

		int c = (N*(N-1))/2 + (M*(M-1))/2;
		System.out.println(c);
		
	}
}
/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