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.Scanner;
public class Solution {

    public static long nCr(int n, int r)
    {
        //System.out.println(n+" "+r);
        // long ans = 1;
        // if (n==r) return ans;
        // for(int i=n, j=1;i>=r && j<=n-r;i--,j++){
        //     ans *= i;
        //     ans /= j;
        // }
        long result = 1;
        for (int i = 0; i < r; ++i)
        {
            result *= (n - i);
            result /= (i + 1);
        }
        return result;
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int t = sc.nextInt();
        long ans = 0;
        if(t>m+n) System.out.println(ans);
        else if(t == m+n) System.out.println(1);
        else{
            for(int i=4;i<=n;i++){
                int j = t - i;
                if(j >= 1){
                    ans += nCr(n,i) * nCr(m,j);
                    //System.out.println(ans+" "+i+" "+j);
                }
            }
            System.out.println(ans);
        }
        
        
    }
}
