import java.util.*;

public class Main {

    public static void main(String [] commandLineArgument){

        Scanner input = new Scanner(System.in);
        int n = input.nextInt() , m = input.nextInt();
        int answer = (m * (m - 1))/2;
        answer += (n * (n - 1))/2;
        System.out.println(answer);
        input.close();

    }

}


/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