import java.io.BufferedReader; 
import java.io.*;
import java.io.InputStreamReader; 
import java.util.Scanner; 
import java.util.StringTokenizer; 
import java.util.*;
import java.math.*;
public class Main 
{ 
    static class FastReader 
    { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader()
        { 
            br = new BufferedReader(new
                     InputStreamReader(System.in)); 
        } 
  
        String next()
        { 
            while (st == null || !st.hasMoreElements()) 
            { 
                try
                { 
                    st = new StringTokenizer(br.readLine()); 
                } 
                catch (IOException  e) 
                { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() 
        { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() 
        { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() 
        { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() 
        { 
            String str = ""; 
            try
            { 
                str = br.readLine();
            } 
            catch (IOException e) 
            { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } 
   public static void main(String args[])
    {
        FastReader sc=new FastReader();
        PrintWriter pw=new PrintWriter(System.out);
        int t=1;//sc.nextInt(),k=0;
        long ans=0,mod=1000000007;
        while(t-->0)
        {
        int n=sc.nextInt(),m=sc.nextInt();
        pw.println((n*(n-1))/2 + (m*(m-1))/2);
        }
           pw.close();
    }
}
  
/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