import java.util.Scanner;

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