Problem: Alex enjoys performing magic tricks. He has a trick that requires a deck of n cards. He has m identical decks of n different cards each, which have been mixed together. When Alex wishes to perform the trick, he grabs n cards at random and performs the trick with those. The resulting deck looks like a normal deck, but may have duplicates of some cards.

The trick itself is performed as follows: first Alex allows you to choose a random card from the deck. You memorize the card and put it back in the deck. Then Alex shuffles the deck, and pulls out a card. If the card matches the one you memorized, the trick is successful.

You don't think Alex is a very good magician, and that he just pulls a card randomly from the deck. Determine the probability of the trick being successful if this is the case.

Input

First line of the input consists of two integers n and m (1 ≤ n, m ≤ 1000), separated by space — number of cards in each deck, and number of decks.

Output

On the only line of the output print one floating point number – probability of Alex successfully performing the trick. Relative or absolute error of your answer should not be higher than 10 - 6.

Examples

Input

2 2


Output

0.6666666666666666


Input

4 4


Output

0.4000000000000000


Input

1 2


Output

1.0000000000000000

Note

In the first sample, with probability <image> Alex will perform the trick with two cards with the same value from two different decks. In this case the trick is guaranteed to succeed.

With the remaining <image> probability he took two different cards, and the probability of pulling off the trick is <image>.

The resulting probability is <image>

Solution (in JAVA):

Solution:
/*******************************************************************
My love has gone away,
quietly after a hundered days.
This is what's she has always said she won't stay
for more than what she can repay.

I can still hear her say there
that I'm not hearing tender play
The day she let me kiss her was a display,
of love to those who she betray.

How can I put someone to the test,
when I thought I got the best.
Untill the taste of bitterness then I regret
but still that I won't detest,
the love I can't forget,
like someone who has left.

How can i leave someone for the rest
when i'm alone facing the best
Untill they take some try to reason i regret
But still that i won't detest
who i can never forget
like someone i once met .. 
 ******************************************************************/
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.InputMismatchException;

public class TaskC_452 {
	public static void main(String[] args) {
		input();
		solve();
	}

	static void solve() {
		double res = 1;
		if (n != 1 || m != 1) {
			res = (m - 1) / (m * n - 1) + (m * n - 1 - (m - 1)) / (m * n - 1)
					* (1 / n);
		}
		System.out.println(res);
	}

	/************************************************************************************/
	static double n;
	static double m;

	static void input() {
		n = nextDouble();
		m = nextDouble();
	}

	/************************************************************************************/
	static InputStream is = System.in;
	static private byte[] buffer = new byte[1024];
	static private int lenbuf = 0, ptrbuf = 0;

	static private int readByte() {
		if (lenbuf == -1)
			throw new InputMismatchException();
		if (ptrbuf >= lenbuf) {
			ptrbuf = 0;
			try {
				lenbuf = is.read(buffer);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (lenbuf <= 0)
				return -1;
		}
		return buffer[ptrbuf++];
	}

	static private boolean isSpace(int c) {
		return !(c >= 33 && c <= 126);
	}

	static private int read() {
		int b;
		while ((b = readByte()) != -1 && isSpace(b))
			;
		return b;
	}

	static private double nextDouble() {
		return Double.parseDouble(nextString());
	}

	static private char nextChar() {
		return (char) read();
	}

	static private String nextString() {
		int b = read();
		StringBuilder sb = new StringBuilder();
		while (!(isSpace(b))) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	static private char[] nextString(int n) {
		char[] buf = new char[n];
		int b = read(), p = 0;
		while (p < n && !(isSpace(b))) {
			buf[p++] = (char) b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}

	static private int nextInt() {
		int num = 0, b;
		boolean minus = false;
		while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
			;
		if (b == '-') {
			minus = true;
			b = readByte();
		}

		while (true) {
			if (b >= '0' && b <= '9') {
				num = num * 10 + (b - '0');
			} else {
				return minus ? -num : num;
			}
			b = readByte();
		}
	}

	private long nextLong() {
		long num = 0;
		int b;
		boolean minus = false;
		while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
			;
		if (b == '-') {
			minus = true;
			b = readByte();
		}

		while (true) {
			if (b >= '0' && b <= '9') {
				num = num * 10 + (b - '0');
			} else {
				return minus ? -num : num;
			}
			b = readByte();
		}
	}

	static private int[] nextAi(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = nextInt();
		return a;
	}

}