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 MainClass {
	
	public static final int maxn = 31;
	
	public static void main(String[] args) {
		Locale.setDefault(Locale.US);
		Scanner in = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		MainClass solution = new MainClass();
		solution.run(in, out);
		in.close();
		out.close();
	}
	
	public void run(Scanner in, PrintWriter out) {
		int n = in.nextInt();
		int m = in.nextInt();
		int t = in.nextInt();
		long[][] C = new long[maxn][maxn];
		C[0][0] = 1;
		for (int i = 0; i < maxn; i++)
			C[i][0] = C[i][i] = 1;
		for (int i = 1; i < maxn; i++)
			for (int j = 1; j < i; j++)
				C[i][j] = C[i - 1][j] + C[i - 1][j - 1];  
		long ans = 0;
		for (int i = 4; i <= n; i++) {
			int j = t - i;
			if (j >= 1 && j <= m)
				ans += C[n][i] * C[m][j];
		}
		out.print(ans);
	}
	
	
}