import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int n = scan.nextInt();
		int m = scan.nextInt();
		
		int count = 0;
		for (int i = 1; i <= n - 1; i++) {
			count+= i;
		}
		for (int i = 1; i <= m - 1; i++) {
			count+= i;
		}
		System.out.println(count);
	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int n = scan.nextInt();
		int m = scan.nextInt();
		
		int count = 0;
		for (int i = 1; i <= n - 1; i++) {
			count+= i;
		}
		for (int i = 1; i <= m - 1; i++) {
			count+= i;
		}
		System.out.println(count);
	}

} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int n = scan.nextInt();
		int m = scan.nextInt();
		
		int count = 0;
		for (int i = 1; i <= n - 1; i++) {
			count+= i;
		}
		for (int i = 1; i <= m - 1; i++) {
			count+= i;
		}
		System.out.println(count);
	} main {
		Scanner scan = new Scanner(System.in);
		
		int n = scan.nextInt();
		int m = scan.nextInt();
		
		int count = 0;
		for (int i = 1; i <= n - 1; i++) {
			count+= i;
		}
		for (int i = 1; i <= m - 1; i++) {
			count+= i;
		}
		System.out.println(count);
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan int m = scan.nextInt(); m scan.nextInt() scan.nextInt scan int count = 0; count 0 for (int i = 1; i <= n - 1; i++) {
			count+= i;
		} int i = 1; int i = 1; i 1 i <= n - 1 i n - 1 n 1 i++ i++ i {
			count+= i;
		} {
			count+= i;
		} count+= i count i for (int i = 1; i <= m - 1; i++) {
			count+= i;
		} int i = 1; int i = 1; i 1 i <= m - 1 i m - 1 m 1 i++ i++ i {
			count+= i;
		} {
			count+= i;
		} count+= i count i System.out.println(count) System.out.println System.out System System.out count String[] args args public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int n = scan.nextInt();
		int m = scan.nextInt();
		
		int count = 0;
		for (int i = 1; i <= n - 1; i++) {
			count+= i;
		}
		for (int i = 1; i <= m - 1; i++) {
			count+= i;
		}
		System.out.println(count);
	}

} public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int n = scan.nextInt();
		int m = scan.nextInt();
		
		int count = 0;
		for (int i = 1; i <= n - 1; i++) {
			count+= i;
		}
		for (int i = 1; i <= m - 1; i++) {
			count+= i;
		}
		System.out.println(count);
	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int n = scan.nextInt();
		int m = scan.nextInt();
		
		int count = 0;
		for (int i = 1; i <= n - 1; i++) {
			count+= i;
		}
		for (int i = 1; i <= m - 1; i++) {
			count+= i;
		}
		System.out.println(count);
	}

}
