import java.util.*;
public class Main
{
  public static void main(String args[])
  {
    Scanner in=new Scanner(System.in);
    int N=in.nextInt();int i,j,f=0;
    int M=in.nextInt();
    for(i=1;i<=N;i++)
    {
      for(j=i+1;j<=N;j++)
        f++;
    }
    for(i=1;i<=M;i++)
    {
      for(j=i+1;j<=M;j++)
        f++;
    }
    System.out.println(f);
  }
}
      
    
/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