import java.util.Scanner;

public class Main {

    private static Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {

        solve();
    }

    private static void solve() {

        int n = scanner.nextInt();
        int m = scanner.nextInt();

        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