import java.io.*;
import java.util.*;
import java.lang.Math;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int ans = a * (a-1) + b * (b-1);
        ans /= 2;
        System.out.println(ans);
    }
} import java.io.*; io.* java import java.util.*; util.* java import java.lang.Math; Math java.lang public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int ans = a * (a-1) + b * (b-1);
        ans /= 2;
        System.out.println(ans);
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int ans = a * (a-1) + b * (b-1);
        ans /= 2;
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int ans = a * (a-1) + b * (b-1);
        ans /= 2;
        System.out.println(ans);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc int ans = a * (a-1) + b * (b-1); ans a * (a-1) + b * (b-1) a * (a-1) a (a-1) a 1 b * (b-1) b (b-1) b 1 ans /= 2 ans 2 System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int ans = a * (a-1) + b * (b-1);
        ans /= 2;
        System.out.println(ans);
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int ans = a * (a-1) + b * (b-1);
        ans /= 2;
        System.out.println(ans);
    }
} Main
import java.io.*;
import java.util.*;
import java.lang.Math;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int ans = a * (a-1) + b * (b-1);
        ans /= 2;
        System.out.println(ans);
    }
}
