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.* ;
import java.math.* ;


public class Main {

	/**
	 * @param args
	 * @throws IOException 
	 */
	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub

		SolveProblem solveProblem = new SolveProblem();
		solveProblem.solve();
	}

}

class SolveProblem
{
	BigInteger f( int n , int k )
	{
		BigInteger value = new BigInteger( "1" );
		if ( n < k ) return new BigInteger( "0" );
		for ( int i = 2 ; i <= n ; i++ )
			value = value.multiply( new BigInteger( i+"" ) );
		for ( int i = 2 ; i <= k ; i++ )
			value = value.divide( new BigInteger( i+"" ) );
		for ( int i = 2 ; i <= n-k ; i++ )
			value = value.divide( new BigInteger( i+"" ) );
		return value;
	}
	
	public void solve() throws IOException
	{
		BufferedReader in  = new BufferedReader( new InputStreamReader( System.in ) );
		PrintStream    out = new PrintStream( System.out );
		String[] s = in.readLine().split( " " );
		int n = toInt( s[0] );
		int m = toInt( s[1] );
		int t = toInt( s[2] );
		BigInteger solve = new BigInteger( "0" );
		for ( int p = 1 ; p <= t-4 ; p++ )
		{
			BigInteger a = f( n , t-p );
			BigInteger b = f( m , p );
			solve = solve.add( a.multiply( b ) );
		}
		out.println( solve );
	}
	
	private int toInt( String value )
	{
		return Integer.parseInt( value );
	}
}
