import java.util.*;
class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int ans;
        if(n<1){
            ans = m*(m-1)/2;
        } else if(m<1){
            ans = n*(n-1)/2;
        } else {
            ans = n*(n-1)/2+m*(m-1)/2;
        }
        System.out.println(ans);
    }
} import java.util.*; util.* java class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int ans;
        if(n<1){
            ans = m*(m-1)/2;
        } else if(m<1){
            ans = n*(n-1)/2;
        } else {
            ans = n*(n-1)/2+m*(m-1)/2;
        }
        System.out.println(ans);
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int ans;
        if(n<1){
            ans = m*(m-1)/2;
        } else if(m<1){
            ans = n*(n-1)/2;
        } else {
            ans = n*(n-1)/2+m*(m-1)/2;
        }
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int ans;
        if(n<1){
            ans = m*(m-1)/2;
        } else if(m<1){
            ans = n*(n-1)/2;
        } else {
            ans = n*(n-1)/2+m*(m-1)/2;
        }
        System.out.println(ans);
    } 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 int ans; ans if(n<1){
            ans = m*(m-1)/2;
        } else if(m<1){
            ans = n*(n-1)/2;
        } else {
            ans = n*(n-1)/2+m*(m-1)/2;
        } n<1 n 1 {
            ans = m*(m-1)/2;
        } ans = m*(m-1)/2 ans m*(m-1)/2 m*(m-1) m (m-1) m 1 2 if(m<1){
            ans = n*(n-1)/2;
        } else {
            ans = n*(n-1)/2+m*(m-1)/2;
        } m<1 m 1 {
            ans = n*(n-1)/2;
        } ans = n*(n-1)/2 ans n*(n-1)/2 n*(n-1) n (n-1) n 1 2 {
            ans = n*(n-1)/2+m*(m-1)/2;
        } ans = n*(n-1)/2+m*(m-1)/2 ans n*(n-1)/2+m*(m-1)/2 n*(n-1)/2 n*(n-1) n (n-1) n 1 2 m*(m-1)/2 m*(m-1) m (m-1) m 1 2 System.out.println(ans) System.out.println System.out System System.out ans String[] args args
import java.util.*;
class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int ans;
        if(n<1){
            ans = m*(m-1)/2;
        } else if(m<1){
            ans = n*(n-1)/2;
        } else {
            ans = n*(n-1)/2+m*(m-1)/2;
        }
        System.out.println(ans);
    }
}