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.math.*;
import java.util.*;

public class Main{
	public static BigInteger cal(int n,int m) {
		BigInteger s = BigInteger.valueOf(1);
		int  i,j;
		for (i = n,j = m; j > 0;i--,j--) {
			s = s.multiply(BigInteger.valueOf(i));
		}
		for (i=1; i <= m ;i++) {
			s = s.divide(BigInteger.valueOf(i));
		}
		return s;
	}
	public static void main(String[] args) {
		Scanner cin = new Scanner(new BufferedInputStream(System.in));
		int n,m,t;
		n = cin.nextInt();
		m = cin.nextInt();
		t = cin.nextInt();
		BigInteger ans = BigInteger.valueOf(0);
		int i,j;
		for (i = 4; i<=n;i++) {
			if (t-i>=1 && t-i<=m) {
				BigInteger a = cal(n,i);
				BigInteger b = cal(m,t - i);
				a = a.multiply(b);
				ans = ans.add(a);
			}
		}
		System.out.println(ans);
		//System.out.println(cal(3,3));
	}
}
