NoSuchElementException on running code with window handlers

Following is my code
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[b:2r6u602o]Query :My code seems ok.But i get NoSuchElement Exception.[/b:2r6u602o]

package p1;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.concurrent.TimeUnit;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.FirefoxDriver;

public class TimesOFWindow {
public static WebDriver w=new FirefoxDriver();
public static void main(String[] args) {
// TODO Auto-generated method stub


w.navigate().to("http://timesofindia.indiatimes.com");
w.manage().timeouts().implicitlyWait(30, TimeUnit.MILLISECONDS);
w.findElement(By.xpath("//a[text()='India']")).click();
w.navigate().back();
w.manage().timeouts().implicitlyWait(30, TimeUnit.MILLISECONDS);
WebElement Box= w.findElement(By.xpath("//*[@id='footer']/div[2]/div/div[1]/div[1]"));


Box.findElement(By.xpath("//a[text()='Indiatimes']")).click();
Set <String> s =new HashSet<String>();
Iterator <String>it=s.iterator();
s=w.getWindowHandles();
System.out.println(s.size());

Object[] WinIDs=new Object[s.size()];
//WinIDs[0]=w.getWindowHandle();
String mainWindow=it.next();
String childwin=it.next();
System.out.println(mainWindow);
System.out.println(childwin);

}}