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 C {

	public C () throws IOException {
		int n = sc.nextInt();
		int m = sc.nextInt();
		int t = sc.nextInt();
		solve(n,m,t);
	}
	
	public void solve (int n, int m, int t) {
		long [][] C = new long [31][31];
		for (int i = 0; i <= 30; ++i)
			C[i][0] = C[i][i] = 1L;
		
		for (int i = 1; i <= 30; ++i) 
			for (int j = 1; j < i; ++j)
				C[i][j] = C[i-1][j-1] + C[i-1][j];
		
		long S = 0L;
		for (int b = 4; b < t; ++b)
			if (b <= n && t-b <= m)
				S += C[n][b] * C[m][t-b];
		
		print(S);
	}
	
	////////////////////////////////////////////////////////////////////////////////////

	static Scanner sc;
	
	static void print (Object o) {
		System.out.println(o);
	}
	
	static void run () throws IOException {
		sc = new Scanner(System.in);
		new C();
	}
	
	public static void main(String[] args) throws IOException {
		run();
	}
}
