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
//package CF;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;

public class A {
    static long [][] comb;
    static long nCr(int n, int k)
    {
	if(k > n)
	    return 0;
	if(k == 0 || k == n)
	    return 1;
	if(comb[n][k] != -1)
	    return comb[n][k];
	if(n-k < k)
	    return comb[n][k] = nCr(n, n-k);
	return comb[n][k] = nCr(n-1, k-1) + nCr(n-1, k);
    }
    public static void main(String[] args) throws Exception
    {
	Scanner bf = new Scanner(System.in);
	PrintWriter out = new PrintWriter(System.out);
	int n = bf.nextInt(), m = bf.nextInt(), k = bf.nextInt();
	comb = new long[n+m+1][k+1];
	for(long [] i:comb)
	    Arrays.fill(i, -1);
	long tmp = 0;
	for (int i = 0; i < 4; i++)
	{
	    tmp += nCr(n, i)*nCr(m, k-i);
	}
	out.println(nCr(n+m, k)-tmp-nCr(n, k));
	out.flush();
	out.close();
    }

    static class Scanner {
	StringTokenizer st;
	BufferedReader br;

	public Scanner(InputStream s)
	{
	    br = new BufferedReader(new InputStreamReader(s));
	}

	public Scanner(FileReader fileReader)
	{
	    br = new BufferedReader(fileReader);
	}

	public String next() throws IOException
	{
	    while (st == null || !st.hasMoreTokens())
		st = new StringTokenizer(br.readLine());
	    return st.nextToken();
	}

	public int nextInt() throws IOException
	{
	    return Integer.parseInt(next());
	}

	public long nextLong() throws IOException
	{
	    return Long.parseLong(next());
	}

	public String nextLine() throws IOException
	{
	    return br.readLine();
	}

	public boolean ready() throws IOException
	{
	    return br.ready();
	}
    }
}