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 {
    public static BigInteger A(int a,int b)
    {
        if (b<=0) return BigInteger.ONE;
        else return fact(a).divide(fact(a-b)).divide(fact(b));
    }
    public static BigInteger fact(int x)
    {
        BigInteger res=BigInteger.ONE;
        for (int i=2; i<=x;i++)
        {
            res=res.multiply(new BigInteger(String.valueOf(i)));
        }
        return new BigInteger(String.valueOf(res));
    }
    public static void main(String[] args) throws IOException {
        BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out=new PrintWriter(System.out);
        String[] input=in.readLine().split(" ");
        int n=Integer.parseInt(input[0]);
        int m=Integer.parseInt(input[1]);
        int t=Integer.parseInt(input[2]);
        BigInteger res=BigInteger.ZERO;
        for(int i=4; i<=n; i++)
            for (int j=1;j<=m; j++)
                if (i+j==t) 
                    {
                        res=res.add(A(n,i).multiply(A(m,j)));
                    }
        
        out.print(res);
        out.close();
    }
}