import 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();
		if (N==1 && M==1) {
			System.out.println(0);
		} else {
			System.out.println((N*(N-1)/2)+(M*(M-1)/2));
		}
		
			
		
		
      	sc.close();
    }
		
		
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
      	
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		if (N==1 && M==1) {
			System.out.println(0);
		} else {
			System.out.println((N*(N-1)/2)+(M*(M-1)/2));
		}
		
			
		
		
      	sc.close();
    }
		
		
} Main public static void main(String[] args){
      	
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		if (N==1 && M==1) {
			System.out.println(0);
		} else {
			System.out.println((N*(N-1)/2)+(M*(M-1)/2));
		}
		
			
		
		
      	sc.close();
    } main {
      	
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		if (N==1 && M==1) {
			System.out.println(0);
		} else {
			System.out.println((N*(N-1)/2)+(M*(M-1)/2));
		}
		
			
		
		
      	sc.close();
    } 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 if (N==1 && M==1) {
			System.out.println(0);
		} else {
			System.out.println((N*(N-1)/2)+(M*(M-1)/2));
		} N==1 && M==1 N==1 N 1 M==1 M 1 {
			System.out.println(0);
		} System.out.println(0) System.out.println System.out System System.out 0 {
			System.out.println((N*(N-1)/2)+(M*(M-1)/2));
		} System.out.println((N*(N-1)/2)+(M*(M-1)/2)) System.out.println System.out System System.out (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 sc.close() sc.close sc String[] args args public class Main {
	public static void main(String[] args){
      	
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		if (N==1 && M==1) {
			System.out.println(0);
		} else {
			System.out.println((N*(N-1)/2)+(M*(M-1)/2));
		}
		
			
		
		
      	sc.close();
    }
		
		
} public class Main {
	public static void main(String[] args){
      	
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		if (N==1 && M==1) {
			System.out.println(0);
		} else {
			System.out.println((N*(N-1)/2)+(M*(M-1)/2));
		}
		
			
		
		
      	sc.close();
    }
		
		
} Main
import 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();
		if (N==1 && M==1) {
			System.out.println(0);
		} else {
			System.out.println((N*(N-1)/2)+(M*(M-1)/2));
		}
		
			
		
		
      	sc.close();
    }
		
		
}
