    import java.io.*;
	import java.util.*;
    class Main
    {
      public static void main(String args[])throws IOException
      {
        int i,s1=0,s2=0,s,m,n;
        BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
        Scanner sc =new Scanner(System.in);
        //n=Integer.parseInt(input.readLine());
        //m=Integer.parseInt(input.readLine());
        n=sc.nextInt();
        m=sc.nextInt();
        for(i=1;i<m;i++)
        {
          s1=s1+i;
        }
        for(i=1;i<n;i++)
        {
          s2=s2+i;
        }
        s=s1+s2;
        System.out.println(s);
      }
    }
/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