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 javafx.geometry.Pos;
import org.omg.Messaging.SYNC_WITH_TRANSPORT;

import java.awt.image.VolatileImage;
import java.io.*;
import java.math.BigInteger;
import java.util.*;
import static java.lang.System.out;
import static java.lang.System.setProperty;


public  class Main {
    public static long combination(long n, long k)
    {
        if(n==k)return 1;
        return (long)(permutation(n) / (permutation(k) * permutation(n - k)));
    }

    public static long permutation(long i)
    {
        if (i == 1)
        {
            return 1;
        }
        return (long)(i * permutation(i - 1));
    }
    public static BigInteger binomial(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;
    }
    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        Scanner S = new Scanner(System.in);
        BufferedReader BR = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter PW = new PrintWriter(new OutputStreamWriter(out));
        long b=S.nextInt(),g=S.nextInt(),all=S.nextInt();
        long ans=(long)0;
        for (int i=4;i<all;i++) {
                 if(i>b||((all-i)>0&&(all-i)>g)||(all-i)<1)continue;
                 long comb=binomial((int)b,i).longValue();long comg=binomial((int)g, (int) (all-i)).longValue();
                 ans+=(comb*comg);

            }
            System.out.print(ans);
        }



}