import java.util.Scanner;

public class Main { public static void main(String...args) {
    Scanner sc = new Scanner(System.in); int N = sc.nextInt(); int M = sc.nextInt();
    System.out.println(N * (N - 1) / 2 + M * (M - 1) / 2);}
}
/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