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.util.*;

public class Main {

    public static void main(String[] args) throws Exception {
        PrintWriter pr = new PrintWriter(System.out, true);
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(in.readLine());
        //Scanner s = new Scanner(System.in);
        int n = Integer.parseInt(st.nextToken());
        int m = Integer.parseInt(st.nextToken());
        int t = Integer.parseInt(st.nextToken());
        int[][] C = new int[31][31];
        for (int i = 0; i < 31; i++) {
            for (int j = 0; j < 31; j++) {
                C[i][j] = 1;
            }
        }
        for (int i = 2; i < 31; i++) {
            for (int j = 1; j < i; j++) {
                C[i][j] = C[i - 1][j - 1] + C[i - 1][j];
            }
        }
        /*for (int i = 0; i < 31; i++) {
            pr.println(Arrays.toString(C[i]));
        }*/
        long res = 0;
        for (int i = Math.min(t - 4, m); i > 0 && i + n >= t; i--) {
        //pr.println(i);
        res += (long)C[m][i] * C[n][t - i];
        }
        pr.println(res);
    }
}