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 sum = 0;
		if (n >= 2) {
			sum += n * n / 2 - (n / 2);
		}
		if (m >= 2) {
			sum += m * m / 2 - (m / 2);
		}
		System.out.println(sum);
	}
} 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 sum = 0;
		if (n >= 2) {
			sum += n * n / 2 - (n / 2);
		}
		if (m >= 2) {
			sum += m * m / 2 - (m / 2);
		}
		System.out.println(sum);
	}
} Main public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int m = scan.nextInt();
		int sum = 0;
		if (n >= 2) {
			sum += n * n / 2 - (n / 2);
		}
		if (m >= 2) {
			sum += m * m / 2 - (m / 2);
		}
		System.out.println(sum);
	} main {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int m = scan.nextInt();
		int sum = 0;
		if (n >= 2) {
			sum += n * n / 2 - (n / 2);
		}
		if (m >= 2) {
			sum += m * m / 2 - (m / 2);
		}
		System.out.println(sum);
	} 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 sum = 0; sum 0 if (n >= 2) {
			sum += n * n / 2 - (n / 2);
		} n >= 2 n 2 {
			sum += n * n / 2 - (n / 2);
		} sum += n * n / 2 - (n / 2) sum n * n / 2 - (n / 2) n * n / 2 n * n n n 2 (n / 2) n 2 if (m >= 2) {
			sum += m * m / 2 - (m / 2);
		} m >= 2 m 2 {
			sum += m * m / 2 - (m / 2);
		} sum += m * m / 2 - (m / 2) sum m * m / 2 - (m / 2) m * m / 2 m * m m m 2 (m / 2) m 2 System.out.println(sum) System.out.println System.out System System.out sum 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 sum = 0;
		if (n >= 2) {
			sum += n * n / 2 - (n / 2);
		}
		if (m >= 2) {
			sum += m * m / 2 - (m / 2);
		}
		System.out.println(sum);
	}
} public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int m = scan.nextInt();
		int sum = 0;
		if (n >= 2) {
			sum += n * n / 2 - (n / 2);
		}
		if (m >= 2) {
			sum += m * m / 2 - (m / 2);
		}
		System.out.println(sum);
	}
} 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 sum = 0;
		if (n >= 2) {
			sum += n * n / 2 - (n / 2);
		}
		if (m >= 2) {
			sum += m * m / 2 - (m / 2);
		}
		System.out.println(sum);
	}
}