import java.util.*;
public class Main
 {
     public static void main(String[] args)
   {
     Scanner s=new Scanner(System.in);
     int n=s.nextInt();
     int m=s.nextInt();
     int ans=0;
    ans=(n*(n-1)/2)+(m*(m-1)/2);
    System.out.println(ans);
   } 
}
/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