import java.util.*;

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

} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt(), m = scanner.nextInt();
        int sum = 0;
        for (int i = 1; i < n; i ++)
            sum += i;
        for (int j = 1; j < m; j ++)
            sum += j;
        System.out.println(sum);
    }

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

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

} Main
import java.util.*;

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

}
