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
//http://codeforces.com/problemset/problem/131/C

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

public class Theatre
{

    static long triangle[][]= new long[55][55];
    public static void main(String args[])
    {
        Scanner fin = new Scanner(System.in);
        
        final int MIN_BOYS = 4;
        final int MIN_GIRLS = 1;

        int boys = fin.nextInt();
        int girls = fin.nextInt();

        int total = fin.nextInt();
        
        int spaces = total - MIN_BOYS - MIN_GIRLS;

        int left_over_boys = boys - MIN_BOYS;
        int left_over_girls = girls - MIN_GIRLS;

        long combinations = 0;
        
        //long triangle[][]= new long[55][55];

        build_pascal_triangle(45);

        //System.out.println(combination(0, 0));
        //System.out.println(combination(2, 1));
        //System.out.println(combination(6, 3));
        

        for(int b = 4; b <= boys; ++b)
        {
            int g = total - b;

            //System.out.println(b + " " + g);
            
            if(g >= 1 && g <= girls)
            {
                

                //System.out.println(factorial(boys, boys - b) + " " + factorial(boys - b, 1));
                long boy_comb = combination(boys, b);
                long girl_comb = combination(girls, g);
                //System.out.println(boy_comb + " " + girl_comb);
                combinations += boy_comb * girl_comb;
            }
        }
        
        System.out.println(combinations);

        
    }

    public static void build_pascal_triangle(int levels)
    {
        triangle[0][0] = 1;
        triangle[1][0] = 1;
        triangle[1][1] = 1;
        for(int i = 2; i < levels; ++i)
        {
            triangle[i][0] = 1;
            triangle[i][i] = 1;
            //System.out.print("1 "); 
            for(int j = 1; j < i; ++j)
            {
                triangle[i][j] = triangle[i - 1][j-1] + triangle[i -1][j];
                //System.out.print(triangle[i][j] + " ");
            }
            //System.out.println("1");
            //System.out.println();
        }
    }

    public static long combination(int n, int r)
    {
        return triangle[n][r];
    }
}