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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.Scanner;


public class C {
    
    public int gcd(int a,int b){
        if (b == 0) return a;
        else return gcd(b, a%b);
    }
    public int c(int n,int r){
        int x = Math.max(r, n-r);
        
        int up=1,down=1;
        for (int i=n;i>x;i--){
            up *= i;
            down *= i-x;
            int v = gcd(up,down);
            up /= v;
            down /= v;
        }
        return up/down;
    }
    int n,m,t;
//  int[] a;
//  int x,y,z;
    char[] v = new char[]{'a', 'o', 'y', 'e', 'u', 'i'};
    public void run() throws IOException{
        Scanner s= new Scanner(new InputStreamReader(System.in));
        n = s.nextInt();m = s.nextInt(); t = s.nextInt();
        
        long sum = 0;
        for (int i = 4; i <= n; i++) {
            if (t - i < 1) break;
            if (t-i > m) continue;
            sum += (long)c(n,i) * c(m,t-i);
        }
        System.out.println(sum);
    }
    
    
    public static void main(String[] args) throws IOException {
        (new C()).run();
    }

}
