
import java.util.*;

public class Main {
	static public void main(String args[]){
		Scanner sc=new Scanner(System.in);
		 
		 int n=sc.nextInt();
		 int m=sc.nextInt();
		 if(m<2)m=0;
		 
		 n*=n-1; n/=2;
		 m*=m-1; m/=2;
		 System.out.print(n+m);
	}
}
/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