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.Arrays;
import java.util.Scanner;
import static java.lang.Math.*;

public class c95 {
    public static void debug(Object... obs) {
        System.out.println(Arrays.deepToString(obs));
    }

    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int n=sc.nextInt();
        int m=sc.nextInt();
        int t=sc.nextInt();
        
        long[][]triangle=new long[31][61];
        
        triangle[0][0]=1;
        
        for(int i=1;i<=30;i++)
        {
            triangle[i][0]=1;
            triangle[i][i]=1;
            for(int j=1;j<i;j++)
            {
                triangle[i][j]=triangle[i-1][j] + triangle[i-1][j-1];
            }
        }
        
        //debug(triangle);
        
        long res=0;
        
        for(int k=4;k<=t-1;k++)
        {
            res += triangle[n][k] * triangle[m][t-k];
        }
        
        System.out.println(res);
    }
}
