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
/**
 * Created by IntelliJ IDEA.
 * User: Taras_Brzezinsky
 * Date: 11/25/11
 * Time: 5:48 PM
 * To change this template use File | Settings | File Templates.
 */

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.FileReader;
import java.io.IOException;
import java.math.BigInteger;
import java.util.*;

public class TaskC extends Thread {
    public TaskC(int type) {
        try {
            if (type == 0) {
                this.input = new BufferedReader(new InputStreamReader(System.in));
                this.output = new PrintWriter(System.out);
            } else {
                this.input = new BufferedReader(new FileReader(INPUT_FILE));
                this.output = new PrintWriter(OUTPUT_FILE);
            }
            this.setPriority(Thread.MAX_PRIORITY);
        } catch (Throwable e) {
            e.printStackTrace();
            System.exit(666);
        }
    }

    private void solve() throws Throwable {
        long C[][] = new long[61][61];
        for (int i = 0; i < C.length; ++i) {
            C[i][0] = C[i][i] = 1;
            for (int j = 1; j < i; ++j) {
                C[i][j] = C[i - 1][j - 1] + C[i - 1][j];
            }
        }
        long result = 0;
        int n = nextInt(), m = nextInt(), t = nextInt();
        for (int i = Math.min(t, m); i >= 1; --i) {
            int rest = t - i;
            if (rest < 4) {
                continue;
            }
            result += C[m][i] * C[n][rest];
        }
        output.println(result);
    }

    public void run() {
        try {
            solve();
        } catch (Throwable e) {
            System.err.println(e.getMessage());
            e.printStackTrace();
            System.exit(666);
        } finally {
            output.flush();
            output.close();
        }
    }

    public static void main(String[] args) {
        new TaskC(0).start();
    }

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

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

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

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

    private static final String INPUT_FILE = null;
    private static final String OUTPUT_FILE = null;
    private BufferedReader input;
    private PrintWriter output;
    private StringTokenizer tokens = null;
}