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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class TaskC implements Runnable
{
    private long cnk(int n, int k)
    {
        int big = Math.max(k, n-k);
        int small = Math.min(k, n-k);
        long p = 1;
        for (int i = big + 1; i <= n; i++)
            p = p*i;
        for (int i = 2; i <= small; i++)
            p = p/i;
        return p;
    }

    private void solve() throws IOException
    {
        int n = nextInt();
        int m = nextInt();
        int t = nextInt();
        int start = Math.max(4, t-m);
        int finish = Math.min(n, t-1);
        long res = 0;
        if (start <=finish)
        {
            long cn = cnk(n, start);
            long cm = cnk(m, t-start);
            res = cn*cm;
            for (int i = start+1; i <= finish; i++)
            {
                cn = cn*(n-(i-1))/i;
                cm = cm*(t-(i-1))/(m-(t-i));
                res += cn*cm;
            }
        }
        writer.print(res);
    }

    public static void main(String[] args)
    {
        new TaskC().run();
    }

    BufferedReader reader;
    StringTokenizer tokenizer;
    PrintWriter writer;

    public void run()
    {
        try
        {
            reader = new BufferedReader(new InputStreamReader(System.in));
            tokenizer = null;
            writer = new PrintWriter(System.out);
            solve();
            reader.close();
            writer.close();
        } catch (Exception e)
        {
            e.printStackTrace();
            System.exit(1);
        }
    }

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

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

    double nextDouble() throws IOException
    {
        return Double.parseDouble(nextToken());
    }

    String nextToken() throws IOException
    {
        while (tokenizer == null || !tokenizer.hasMoreTokens())
        {
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }
}