import java.util.*;

public class Main {
    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int M = sc.nextInt();
        sc.close();

        int sum = 0;
        for (int i = 1; i < N; i++) {
            sum += i;
        }
        for (int i = 1; i < M; i++) {
            sum += i;
        }
        System.out.println(sum);
    }
} import java.util.*; util.* java public class Main {
    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int M = sc.nextInt();
        sc.close();

        int sum = 0;
        for (int i = 1; i < N; i++) {
            sum += i;
        }
        for (int i = 1; i < M; i++) {
            sum += i;
        }
        System.out.println(sum);
    }
} Main public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int M = sc.nextInt();
        sc.close();

        int sum = 0;
        for (int i = 1; i < N; i++) {
            sum += i;
        }
        for (int i = 1; i < M; i++) {
            sum += i;
        }
        System.out.println(sum);
    } main {
        final Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int M = sc.nextInt();
        sc.close();

        int sum = 0;
        for (int i = 1; i < N; i++) {
            sum += i;
        }
        for (int i = 1; i < M; i++) {
            sum += i;
        }
        System.out.println(sum);
    } final 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 sc.close() sc.close sc 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 sum i for (int i = 1; i < M; i++) {
            sum += i;
        } int i = 1; int i = 1; i 1 i < M i M i++ i++ i {
            sum += i;
        } {
            sum += i;
        } sum += i sum i System.out.println(sum) System.out.println System.out System System.out sum final String[] args args public class Main {
    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int M = sc.nextInt();
        sc.close();

        int sum = 0;
        for (int i = 1; i < N; i++) {
            sum += i;
        }
        for (int i = 1; i < M; i++) {
            sum += i;
        }
        System.out.println(sum);
    }
} public class Main {
    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int M = sc.nextInt();
        sc.close();

        int sum = 0;
        for (int i = 1; i < N; i++) {
            sum += i;
        }
        for (int i = 1; i < M; i++) {
            sum += i;
        }
        System.out.println(sum);
    }
} Main
import java.util.*;

public class Main {
    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int M = sc.nextInt();
        sc.close();

        int sum = 0;
        for (int i = 1; i < N; i++) {
            sum += i;
        }
        for (int i = 1; i < M; i++) {
            sum += i;
        }
        System.out.println(sum);
    }
}