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.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Task131C {

	public static void main(String... args) throws NumberFormatException,
			IOException {
		Solution.main(System.in, System.out);
	}

	static class Solution {

		static long combinations(int n, int k) {
			long retVal = 1;
			for (int i = 0; i < k;) {
				retVal *= n - i;
				i++;
				retVal /= i;
			}
			return retVal;
		}

		public static void main(InputStream is, OutputStream os)
				throws NumberFormatException, IOException {
			PrintWriter pw = new PrintWriter(os);
			Scanner s = new Scanner(is);

			int n = s.nextInt();
			int m = s.nextInt();
			int t = s.nextInt();

			long retVal = 0;

			for (int boys = 4; boys <= n && t - boys >= 1; boys++) {
				retVal += combinations(n, boys) * combinations(m, t - boys);
			}

			pw.println(retVal);

			pw.flush();
			s.close();
		}
	}

}