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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;
import java.math.BigInteger;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main
{
    public static void main(String[] args)
    {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC
    {
        public void solve(int testNumber, Scanner in, PrintWriter out)
        {
            int T = 1;
            while (T-- > 0)
            {
                solveOne(in, out);
            }
        }

        private void solveOne(Scanner in, PrintWriter out)
        {
            int N = in.nextInt(), M = in.nextInt(), T = in.nextInt();

            BigInteger ans = BigInteger.ZERO;
            for (int boys = 4; boys <= N; boys++)
            {
                for (int girls = 1; girls <= M; girls++)
                {
                    if (boys + girls == T)
                    {
                        BigInteger combBoys = CPUtils.C(N, boys);
                        BigInteger combGirls = CPUtils.C(M, girls);
                        BigInteger mul = combBoys.multiply(combGirls);
                        ans = ans.add(mul);
                    }
                }
            }
            out.println(ans.toString());
        }

    }

    static class CPUtils
    {
        public static BigInteger C(final int N, final int K)
        {
            BigInteger ret = BigInteger.ONE;
            for (int k = 0; k < K; k++)
            {
                ret = ret.multiply(BigInteger.valueOf(N - k))
                         .divide(BigInteger.valueOf(k + 1));
            }
            return ret;
        }

    }
}

