import java.util.Scanner;
public class Main{
    public static void main(String[]args){
        Scanner scan = new Scanner(System.in);
        int n,m,tmpN,tmpM;
        n=scan.nextInt();
        m=scan.nextInt();
        tmpM=0;
        tmpN=0;
        for(int i=1;i<n;i++){
            tmpN +=i;
        }
        for(int i=1;i<m;i++){
            tmpM += i;
        }
        System.out.println(tmpM+tmpN);
    }
}
/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