There are n boys and m girls attending a theatre club. To set a play "The Big Bang Theory", they need to choose a group containing exactly t actors containing no less than 4 boys and no less than one girl. How many ways are there to choose a group? Of course, the variants that only differ in the composition of the troupe are considered different.

Perform all calculations in the 64-bit type: long long for С/С++, int64 for Delphi and long for Java.

Input

The only line of the input data contains three integers n, m, t (4 ≤ n ≤ 30, 1 ≤ m ≤ 30, 5 ≤ t ≤ n + m).

Output

Find the required number of ways.

Please do not use the %lld specificator to read or write 64-bit integers in С++. It is preferred to use cin, cout streams or the %I64d specificator.

Examples

Input

5 2 5


Output

10


Input

4 3 5


Output

3
import java.io.*;

/**
 * Codeforces Beta Round #95 (Div. 2), C
 * @author Roman Kosenko <madkite@gmail.com>
 */
public class Main {
	public static void main(String... args) throws IOException {
		long time = 0;
		if(args.length != 0) {
			System.setIn(new FileInputStream(args[0]));
			time = System.currentTimeMillis();
		} else if(!Boolean.parseBoolean(System.getProperty("ONLINE_JUDGE"))) {
			main("in/C131C.1.txt");
			main("in/C131C.2.txt");
			//main("input.txt");
			return;
		}
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] ss = br.readLine().split(" ");
		int n = Integer.parseInt(ss[0]), m = Integer.parseInt(ss[1]), t = Integer.parseInt(ss[2]);
		long result = 0;
		for(int i = 4; i < t; i++) {
			if(i > n || t - i > m)
				continue;
			result += Utils.c(n, i) * Utils.c(m, t - i);
		}
		System.out.println(result);

		if(time != 0)
			System.out.println(System.currentTimeMillis() - time);
	}
}
abstract class Utils {

	public static long c(int n, int k) {
		if(k > n)
			return 0;
		k = Math.max(k, n - k);
		long r = 1, max = Long.MAX_VALUE / n;
		for(int i = k + 1; i <= n; i++) {
			if((r *= i) > max)
				return c(n - 1, k) + c(n - 1, k - 1);
		}
		for(int i = n - k; i > 1; i--)
			r /= i;
		return r;
	}
}
