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.util.Scanner;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.*;
import static java.lang.Math.*;
public class C95 {
	static Scanner in = new Scanner(System.in);
	static PrintWriter w = new PrintWriter(System.out, true);

	static int ni() {
		return in.nextInt();
	}

	static String nl() {
		return in.nextLine();
	}

	public static void main(String[] args) {
		long n = ni(), m = ni(), t = ni();
		solve(n, m, t);
//		for (int i = 4; i <= 30; i++) {
//			for (int j = 1; j <= 30; j++) {
//				for (int t = 5; t <= i+j; t++) {
//					if (solve(i, j, t) <= 0) {
//						w.println(i+" "+j+" "+t);
//					}
//				}
//			}
//		}
	}
	
	static void solve(long n, long m, long t) {
		BigInteger s = BigInteger.valueOf(0L);
		for (long d = 1L; d <= t - 4L; d++) {
			long ld = d;
			if (ld > m) continue;
			if (ld > m/2) ld = m - ld;
			BigInteger vd = BigInteger.valueOf(1L);
			for (long i = m - ld + 1L; i <= m; i++) vd = vd.multiply(BigInteger.valueOf(i));
			for (long i = 2L; i <= ld; i++) vd = vd.divide(BigInteger.valueOf(i));
			BigInteger vm = BigInteger.valueOf(1L);
			long dm = t - d;
			if (dm > n) continue;
			if (dm > n/2) dm = n - dm;
			for (long i = n - dm + 1L; i <= n; i++) vm = vm.multiply(BigInteger.valueOf(i));
			for (long i = 2L; i <= dm; i++) vm = vm.divide(BigInteger.valueOf(i));
			s = s.add(vd.multiply(vm));
		}
		w.println(s);
	}
}
