/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/

package javaapplication1;

import java.io.BufferedReader;
import java.io.InputStreamReader;

/**
*
* @author Satish
*/
public class BinarySearch {
public static final int NOT_FOUND = -1;
public static int binarySearch( Comparable [ ] a, Comparable x )
{
return binarySearch( a, x, 0, a.length -1 );
}

/**
* Hidden recursive routine.
*/
private static int binarySearch( Comparable [ ] a, Comparable x,
int low, int high )
{
if( low > high )
return NOT_FOUND;

int mid = ( low + high ) / 2;

if( a[ mid ].compareTo( x ) < 0 )
return binarySearch( a, x, mid + 1, high );
else if( a[ mid ].compareTo( x ) > 0 )
return binarySearch( a, x, low, mid - 1 );
else
return mid;
}

// Test program
public static void main( String [ ] args )
{
int SIZE = 8;
Comparable [ ] a = new Integer [ SIZE ];
for( int i = 0; i < SIZE; i++ )
a[ i ] = new Integer( i * 2 );
try{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

int num ;
num =Integer.parseInt(br.readLine());
System.out.println( "Found " + num + " at " +
binarySearch( a, new Integer( num ) ) );
}
catch(Exception e)
{}
}
}