import java.util.*;
class Main
{
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int n=s.nextInt();
		int m=s.nextInt();
		int sum=0;
		for(int i=0;i<n;i++)
		{
			sum=sum+i;
		}
		for(int i=0;i<m;i++)
		{
			sum=sum+i;
		}
		System.out.println(sum);
	}
}
/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