import java.util.Scanner;
public class Main{
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        int a=in.nextInt();
        int b=in.nextInt();
        int sum1=0,sum2=0,sum=0;
        a=a-1;b=b-1;
        sum1=(a*(a+1))/2;
        sum2=(b*(b+1))/2;
        sum=sum1+sum2;
        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