import java.io.*;
import java.util.*;
public class Main {
	static Scanner sc;
	static PrintWriter out;
	public static void main(String[] args) throws Exception{
		// TODO Auto-generated method stub
		sc = new Scanner(System.in);
		out = new PrintWriter(System.out);
		int n,m;
		n = sc.nextInt();m = sc.nextInt();
		long ans = n*(n-1)/2 + m*(m-1)/2;
		out.println(ans);
		out.flush();
	} 
	static class Scanner{
		private BufferedReader br;
		private StringTokenizer st;
		public Scanner(InputStream in) {
			br = new BufferedReader(new InputStreamReader(in));
		}
		public String next() throws IOException{
			while(st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}
		public String nextLine() throws IOException {
			return br.readLine();
		}
		public int nextInt() throws IOException{
			return Integer.parseInt(next());
		}
		public long nextLong() throws IOException{
			return Long.parseLong(next());
		}
		public double nextDouble() throws IOException{
			return Double.parseDouble(next());
		}
		public int[] inArr(int n) throws Exception{
			int a [] = new int[n];
			st = new StringTokenizer(br.readLine());
			for(int i=0;i<n;i++) {
				a[i] = Integer.parseInt(st.nextToken());
			}
			return a;
		}
	}
}
/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