import java.util.*;

public class Main {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        
        int num1 = sc.nextInt();
        int num2 = sc.nextInt();
        
        int even = num1 * (num1 - 1) / 2;
        int odd = num2 * (num2 -1) / 2;
      
        // System.out.println(even);
        // System.out.println(odd);
        
        System.out.println(even + odd);
    }
}
/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