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.*;
import java.util.*;

public class taskC {
	public static void main(String[] args) {
		new taskC().run();
	}

	BufferedReader br;
	StringTokenizer in;
	PrintWriter out;

	public String nextToken() throws IOException {
		while (in == null || !in.hasMoreTokens()) {
			in = new StringTokenizer(br.readLine());
		}
		return in.nextToken();
	}

	public int nextInt() throws IOException {
		return Integer.parseInt(nextToken());
	}

	public long nextLong() throws IOException {
		return Long.parseLong(nextToken());
	}

	public double nextDouble() throws IOException {
		return Double.parseDouble(nextToken());
	}

	long[][] c;

	public long c(int n, int k) {
		if (n > 30)
			return 0;
		if (k > 30)
			return 0;
		if (n < k)
			c[n][k] = 0;
		if (n == k)
			c[n][k] = 1;
		if (k == 1)
			c[n][k] = n;
		if (c[n][k] < 0)
			c[n][k] = c(n - 1, k) + c(n - 1, k - 1);
		return c[n][k];
	}

	public void solve() throws IOException {
		int n = nextInt();
		int m = nextInt();
		int t = nextInt();
		long ans = 0;
		c = new long[31][31];
		for (int i = 0; i < 31; i++)
			for (int j = 0; j < 31; j++)
				c[i][j] = -1;
		for (int i = 4; i < t; i++) {
			ans += c(n, i) * c(m, t - i);
		}
		out.println(ans);
	}

	public void run() {
		try {
			br = new BufferedReader(new InputStreamReader(System.in));
			out = new PrintWriter(System.out);
			//br = new BufferedReader(new FileReader("taskC.in"));
			//out = new PrintWriter("taskC.out");

			solve();

			out.close();
		} catch (IOException e) {
			e.printStackTrace();
			System.exit(1);
		}
	}
}