import java.util.*;
 
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		
		if(N == 1 && M == 1){
			System.out.println(0);
		}else if((N == 1 && M == 2) || (N == 2 && M == 1)){
			System.out.println(1);
		}else{
		int n = N * (N - 1) / 2;
		int m = M * (M - 1) / 2;

		System.out.println(n + m);
		}
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		
		if(N == 1 && M == 1){
			System.out.println(0);
		}else if((N == 1 && M == 2) || (N == 2 && M == 1)){
			System.out.println(1);
		}else{
		int n = N * (N - 1) / 2;
		int m = M * (M - 1) / 2;

		System.out.println(n + m);
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		
		if(N == 1 && M == 1){
			System.out.println(0);
		}else if((N == 1 && M == 2) || (N == 2 && M == 1)){
			System.out.println(1);
		}else{
		int n = N * (N - 1) / 2;
		int m = M * (M - 1) / 2;

		System.out.println(n + m);
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		
		if(N == 1 && M == 1){
			System.out.println(0);
		}else if((N == 1 && M == 2) || (N == 2 && M == 1)){
			System.out.println(1);
		}else{
		int n = N * (N - 1) / 2;
		int m = M * (M - 1) / 2;

		System.out.println(n + m);
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int M = sc.nextInt(); M sc.nextInt() sc.nextInt sc if(N == 1 && M == 1){
			System.out.println(0);
		}else if((N == 1 && M == 2) || (N == 2 && M == 1)){
			System.out.println(1);
		}else{
		int n = N * (N - 1) / 2;
		int m = M * (M - 1) / 2;

		System.out.println(n + m);
		} N == 1 && M == 1 N == 1 N 1 M == 1 M 1 {
			System.out.println(0);
		} System.out.println(0) System.out.println System.out System System.out 0 if((N == 1 && M == 2) || (N == 2 && M == 1)){
			System.out.println(1);
		}else{
		int n = N * (N - 1) / 2;
		int m = M * (M - 1) / 2;

		System.out.println(n + m);
		} (N == 1 && M == 2) || (N == 2 && M == 1) (N == 1 && M == 2) N == 1 N 1 M == 2 M 2 (N == 2 && M == 1) N == 2 N 2 M == 1 M 1 {
			System.out.println(1);
		} System.out.println(1) System.out.println System.out System System.out 1 {
		int n = N * (N - 1) / 2;
		int m = M * (M - 1) / 2;

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

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

		System.out.println(n + m);
		}
	}
} Main
import java.util.*;
 
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		
		if(N == 1 && M == 1){
			System.out.println(0);
		}else if((N == 1 && M == 2) || (N == 2 && M == 1)){
			System.out.println(1);
		}else{
		int n = N * (N - 1) / 2;
		int m = M * (M - 1) / 2;

		System.out.println(n + m);
		}
	}
}