import java.util.Scanner;

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

        System.out.println(nC2(n) + nC2(m));
    }
    static int nC2(int n) {
        return n * (n - 1) / 2;
    }
} import java.util.Scanner; Scanner 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();

        System.out.println(nC2(n) + nC2(m));
    }
    static int nC2(int n) {
        return n * (n - 1) / 2;
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();

        System.out.println(nC2(n) + nC2(m));
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();

        System.out.println(nC2(n) + nC2(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 System.out.println(nC2(n) + nC2(m)) System.out.println System.out System System.out nC2(n) + nC2(m) nC2(n) nC2 n nC2(m) nC2 m String[] args args static int nC2(int n) {
        return n * (n - 1) / 2;
    } nC2 {
        return n * (n - 1) / 2;
    } return n * (n - 1) / 2; n * (n - 1) / 2 n * (n - 1) n (n - 1) n 1 2 int n n public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();

        System.out.println(nC2(n) + nC2(m));
    }
    static int nC2(int n) {
        return n * (n - 1) / 2;
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();

        System.out.println(nC2(n) + nC2(m));
    }
    static int nC2(int n) {
        return n * (n - 1) / 2;
    }
} Main
import java.util.Scanner;

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

        System.out.println(nC2(n) + nC2(m));
    }
    static int nC2(int n) {
        return n * (n - 1) / 2;
    }
}
