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.*;
import java.math.BigInteger;
import java.util.*;

public class Main {

    Scanner in;
    PrintWriter out;

    BigInteger fact(long n) {
        BigInteger ans = BigInteger.ONE;
        for (long i = 2; i <= n; i++) {
            ans = ans.multiply(BigInteger.valueOf(i));
        }
        return ans;
    }

    long C(long n, long k) {
        return Long.valueOf(fact(n).divide(fact(k).multiply(fact(n - k)))
                .toString());
    }

    void solve() {
        long n = in.nextLong();
        long m = in.nextLong();
        long t = in.nextLong();
        long ans = 0;
        for (int boys = 4; boys <= t; boys++) {
            int girls = (int) (t - boys);
            if (girls < 1 || girls > m) {
                continue;
            }
            ans += C(n, boys) * C(m, girls);

        }
        out.println(ans);

    }

    void run() {
        in = new Scanner(System.in);
        out = new PrintWriter(System.out);
        try {
            solve();
        } finally {
            out.close();
        }
    }

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