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.util.*;
import java.lang.*;
import java.io.*;

public class Solution {
    static Scanner sc;
    static int n, m, t;
    static long[][] c;
    
    static void mkCoefTable(int maxN, int maxR) {
        c = new long[maxN+1][maxR+1]; // all 0’s
            for (int n = 0; n < maxN; n++) {
                for (int r = 0; r <= n; r++) {
                    if (r == 0 || n == 1) c[n][r] = 1;
                    else c[n][r] = (c[n-1][r-1] + c[n-1][r]);
                    //System.out.print(c[n][r] + " ");
                }
                //System.out.println(); 
            }
    }

    public static void main (String[] args) throws FileNotFoundException {
        //sc = new Scanner(new File("131C.INP"));
        sc = new Scanner(System.in);
        n = sc.nextInt();
        m = sc.nextInt();
        t = sc.nextInt();
        
        mkCoefTable(32, 32);
        
        long sum = 0;
        for (int j = 1; j <= m; j++) {
            for (int i = 4; i <= n; i++) {
                if ((i+j==t)) {
                    // System.out.printf(
//                      "%d, %d -- %d, %d: %d\n",
//                      n, i, m, j, c[n][i] * c[m][j]);
                    sum += c[n][i] * c[m][j];
                }
            }
        }
        System.out.println(sum);
        sc.close();
    }
}