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.*;
import java.io.*; 
import java.math.BigInteger; 
public class Main
{
	static BigInteger[] arr; 
	public static void main(String[]args) throws Exception
	{
		arr = new BigInteger[31];
		arr[0] = BigInteger.ONE;
		arr[1] = BigInteger.ONE;
		
		for(int i=2; i<arr.length; i++)
		{
			BigInteger temp = new BigInteger(i +"");
			arr[i] = temp.multiply(arr[i-1]);
		}
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
		String input = br.readLine();
		StringTokenizer tk = new StringTokenizer(input); 
		
		int n = Integer.parseInt(tk.nextToken());
		int m = Integer.parseInt(tk.nextToken()); 
		int t = Integer.parseInt(tk.nextToken()); 
		
		int start = t-1;
		while(start>n) start--; 
		BigInteger ans = BigInteger.ZERO;
		
		while(true)
		{
			int men = start;
			int women = t-start; 
			if(men<4 || women <1 || men > n || women > m) break; 
			
			BigInteger a = choose(n,men); 
			BigInteger b = choose(m,women); 
			ans = ans.add(a.multiply(b));
			start--; 
		}
		System.out.println(ans);
	}
	
	public static void test()
	{
		System.out.println(Arrays.toString(arr));
	}
	
	public static BigInteger choose(int n, int k)
	{
		return arr[n].divide(arr[n-k].multiply(arr[k])); 
	}
}