import java.util.*;

public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 1000000007;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	int len = (int)1e6 + 1;

	void doIt() {
		int N = sc.nextInt();
		int M = sc.nextInt();
		int ans = (N * (N - 1)) / 2 + (M * (M - 1)) / 2;
		System.out.println(ans);
	}

	
	
	public static void main(String[] args) {
		new Main().doIt();
	}

} import java.util.*; util.* java public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 1000000007;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	int len = (int)1e6 + 1;

	void doIt() {
		int N = sc.nextInt();
		int M = sc.nextInt();
		int ans = (N * (N - 1)) / 2 + (M * (M - 1)) / 2;
		System.out.println(ans);
	}

	
	
	public static void main(String[] args) {
		new Main().doIt();
	}

} Main Scanner sc = new Scanner(System.in); sc new Scanner(System.in) final int MOD = 1000000007; MOD 1000000007 final int MAX = Integer.MAX_VALUE; MAX Integer.MAX_VALUE Integer Integer.MAX_VALUE final long LMAX = Long.MAX_VALUE; LMAX Long.MAX_VALUE Long Long.MAX_VALUE int len = (int)1e6 + 1; len (int)1e6 + 1 (int)1e6 1 void doIt() {
		int N = sc.nextInt();
		int M = sc.nextInt();
		int ans = (N * (N - 1)) / 2 + (M * (M - 1)) / 2;
		System.out.println(ans);
	} doIt {
		int N = sc.nextInt();
		int M = sc.nextInt();
		int ans = (N * (N - 1)) / 2 + (M * (M - 1)) / 2;
		System.out.println(ans);
	} int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int M = sc.nextInt(); M sc.nextInt() sc.nextInt sc int ans = (N * (N - 1)) / 2 + (M * (M - 1)) / 2; ans (N * (N - 1)) / 2 + (M * (M - 1)) / 2 (N * (N - 1)) / 2 (N * (N - 1)) N (N - 1) N 1 2 (M * (M - 1)) / 2 (M * (M - 1)) M (M - 1) M 1 2 System.out.println(ans) System.out.println System.out System System.out ans public static void main(String[] args) {
		new Main().doIt();
	} main {
		new Main().doIt();
	} new Main().doIt() new Main().doIt new Main() String[] args args public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 1000000007;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	int len = (int)1e6 + 1;

	void doIt() {
		int N = sc.nextInt();
		int M = sc.nextInt();
		int ans = (N * (N - 1)) / 2 + (M * (M - 1)) / 2;
		System.out.println(ans);
	}

	
	
	public static void main(String[] args) {
		new Main().doIt();
	}

} public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 1000000007;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	int len = (int)1e6 + 1;

	void doIt() {
		int N = sc.nextInt();
		int M = sc.nextInt();
		int ans = (N * (N - 1)) / 2 + (M * (M - 1)) / 2;
		System.out.println(ans);
	}

	
	
	public static void main(String[] args) {
		new Main().doIt();
	}

} Main
import java.util.*;

public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 1000000007;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	int len = (int)1e6 + 1;

	void doIt() {
		int N = sc.nextInt();
		int M = sc.nextInt();
		int ans = (N * (N - 1)) / 2 + (M * (M - 1)) / 2;
		System.out.println(ans);
	}

	
	
	public static void main(String[] args) {
		new Main().doIt();
	}

}
