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.math.BigInteger; 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
public class doubt
{
	
		
		private static BigInteger computeFact(long num)
		  {
			BigInteger factorial = BigInteger.ONE;
		    for (int i =1 ;i<=(int)num ;i++)
		      {
		    	factorial = factorial.multiply(BigInteger.valueOf(i));
		      } 
		          return factorial;
		    }

	
	private static BigInteger computeCombination(long n, long r)
	{
		BigInteger nFact=computeFact(n);
		BigInteger rFact=computeFact(r);
		BigInteger nMinusRFact=computeFact(n-r);
		//System.out.println(computeFact(n) +" " + computeFact(r) + " " +computeFact(n-r) +" "+ nFact/(rFact*nMinusRFact));
		return nFact.divide(rFact.multiply(nMinusRFact));
 
	}
	private static BigInteger computeNumOfWays(long n,long m, long t)
	{ BigInteger ans=BigInteger.ZERO;
		if(t<5)
		{
			return BigInteger.ZERO;
		}
		if(t==5)
		{
			return computeCombination(n, 4).multiply(computeCombination(m, 1));			
		}
		else
		{
			for(long i=4; i<=t-1 ;i++)
			{   if(n<i)
				continue;
			
			
			    if(m < t-i)
			    	continue;
			    //System.out.println(computeCombination(n, i) + "  " + computeCombination(m, t-i));
			    if(n>=i && m >= t-i)
				ans=ans.add( computeCombination(n, i).multiply( computeCombination(m, t-i)));
			}
          return ans;
		}
	}
	public static void main(String[] args) {
		Scanner s= new Scanner(System.in);
		long n= s.nextLong();
		long m= s.nextLong();
		long t= s.nextLong();
		
		System.out.println(computeNumOfWays(n,m,t));
 
	}
}