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


/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
 
/* Name of the class has to be "Main" only if the class is public. */
public class bbg
{
	public static int result;
 
public static ArrayList<Integer> [] graph;
 
public static int[]cats;
 
public static int vizitat[];
public static int x;
//public static HashMap<String, Integer> map2;
 
 
	public static void main (String[] args) throws java.lang.Exception
{
 
Scanner input=new Scanner(System.in);
 
HashMap<Integer, Integer> contor1= new HashMap<Integer, Integer>();
HashMap<Integer, Integer> contor2= new HashMap<Integer, Integer>();


HashMap<Integer, Integer> map= new HashMap<Integer, Integer>();
HashMap<String, Integer> curatare= new HashMap<String, Integer>();
HashMap<String, Integer> combinari= new HashMap<String, Integer>();
 
 
		

	
int n=input.nextInt();
int m=input.nextInt();
int t=input.nextInt();

//System.out.println(combinari(7,4));


Long mat[][]=new Long [32][32];


for (int j=0;j<=30;j++)
mat[1][j]=1l;

for (int i=2;i<=30;i++)
for(int j=0;j<=30;j++)
 if(j>i) mat[i][j]=0l;
 else if(j==i) mat[i][j]=1l;
 else if(j==0) mat[i][j]=1l;
 else
  mat[i][j]=mat[i-1][j]+ mat[i-1][j-1];
  
  
  
  //System.out.println(mat[7][4]);
  
  

	

	Long raspuns=0L;

	for (int fete=1; fete<= Math.min( m,t-4);  fete++) {


int baieti=t-fete;

		if(baieti<=n  && baieti>=4)
		
		raspuns+=1l*(mat[m][fete]*mat[n][baieti]);

//System.out.println(m+" "+fete+" "+combinari(m,fete));
//System.out.println(n+" "+baieti+" "+combinari(n,baieti));

	}

System.out.println(raspuns);


	
}

public static int combinari (int a, int b){






	if(b==1 || b+1==a) return a;

	else if (b==0|| a==b) return 1;

	else {


	 return combinari (a-1,b)+combinari(a-1,b-1);
	
	
	}


	
		
		}
		
		
		}
