import java.util.*;


// Warning: Printing unwanted or ill-formatted data to output will cause the test cases to fail

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

        // Write your code here

    }
}
/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