import java.io.*;
import java.math.*;
import java.util.*;

public class Main
{
	public static BigInteger combin(int n,int r)
	{
		if(n<r)
			return BigInteger.ZERO;
		if(n==r||r==0)
			return BigInteger.ONE;
		BigInteger numerator = fact(n);
		BigInteger denominator = fact(r).multiply(fact(n-r));
		BigInteger ret = numerator.divide(denominator);
		return ret;
	}
	public static BigInteger fact(int n)
	{
		BigInteger p = new BigInteger("1");
		BigInteger nn = new BigInteger(""+n);
		BigInteger i = new BigInteger("2");
		for(;i.compareTo(nn)<=0;i=i.add(BigInteger.ONE))
			p=p.multiply(i);
		return p;
	}
	public static void main(String[] args) throws IOException 
	{
		BigInteger X,Y,Z,t1,t2;
		int n,m,N,R;
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String str = br.readLine();
		StringTokenizer st = new StringTokenizer(str," ");
		n = Integer.parseInt(st.nextToken());
		m = Integer.parseInt(st.nextToken());
		t1 = new BigInteger(""+(2*n));
		t2 = new BigInteger(""+(2*n*n-n));
		N = n*m + n - 1;
		R = 2*n - 1;
		X = combin(N,R);
		Y = combin(N-m,R).multiply(t1);
		Z = combin(N-2*m,R).multiply(t2);
		BigInteger ans = X.subtract(Y).add(Z);
		System.out.println(ans);
	}
}