import java.io.*;
import java.lang.*;
import java.util.*;
public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String[] s=br.readLine().split(" ");
        int N=Integer.parseInt(s[0]);
        int M=Integer.parseInt(s[1]);
        int 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