import java.util.Arrays;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

//        long start1 = System.currentTimeMillis();
//        long end1 = System.currentTimeMillis();
//        System.out.println("time1: " + (end1 - start1));

        Scanner scanner = new Scanner(System.in);

        String[] inputs = scanner.nextLine().split(" ");

        int n = Integer.parseInt(inputs[0]);
        int m = Integer.parseInt(inputs[1]);

        int result = n * (n - 1) / 2 + m * (m - 1) / 2;

        System.out.println(result);
    }
}
/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