import java.util.*;

class Main {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int m = in.nextInt();
		System.out.println(combination(n,2) + combination(m,2));
	}
	public static long factorial(long n) {
		if (n <= 1)
			return 1;
		else {
			return n * factorial(n - 1);
		}
	}
	public static long combination(long n, long r) {
		long top = n;
		for (int i = 0; i < r - 1; i++) {
			top = top * (--n);
		}
		long bottom = factorial(r);
		return top / bottom;
	}
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz