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.util.*;
// 131С from coderorces.com
// we have n boys, m girls and t-number of people 
// that we need to choose. But we can't take less 
// than 4 boys and 1 girl.

public class Main {
    
    
    public static long f(long n) {
        if (n==0) {
            return 1;
        } else return n*f(n-1);
    }
    
    public static long cnk(long n, long k){
        //return f(n)/(f(n-k)*f(k));
        if (k==0){return 1;}
        else return cnk(n-1,k-1)+cnk(n-1,k);
    }
    public static void main(String[] args) {
        // easy program
        Scanner in = new Scanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        
        // reading number of girls
        int n = in.nextInt();
        // reading number of boys
        int m = in.nextInt();
        // reading group quontity
        int t = in.nextInt();
        
        long cnkArr[][] = new long[62][62];
        
        for(int i=0;i<=n+m;i++){
            cnkArr[0][i]=0;
            cnkArr[i][0]=1;
            
        }
        for (int i=1;i<=n+m;i++){
            for (int j=1;j<=n+m;j++){
                cnkArr[i][j]=cnkArr[i-1][j-1]+cnkArr[i-1][j];
            //out.print(cnkArr[i][j]);
            //out.print(" ");
            }
            //out.println();
        }
        // using founded formulae
        long s = 0;
        for (int i=1;t-i>=4;i++){
           s=s+cnkArr[m][i]*cnkArr[n][t-i]; 
        }
        out.println(s);
        
        out.flush();
    }
}
