import java.util.*;

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		int M = scan.nextInt();

		int sum_n = 0;
		int sum_m = 0;

		if (N > 1 ){
			for (int i = N-1; i > 0; i-- ){
				sum_n += i ;
			}
		}
		if (M > 1 ){
			for (int i = M-1; i > 0; i-- ){
				sum_m += i ;
			}
		}

		System.out.println( sum_m + sum_n );

	}
}
/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