Window Handling & Drop down Method in WebDriver

package window;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.support.ui.Select;

public class WindowHandling {

    public static void main(String[] args) throws InterruptedException
    {
                    WebDriver driver=new FirefoxDriver();
                    driver.get("https://www.irctc.co.in/");
                    driver.findElement(By.linkText("Hotels")).click();
                    //==================window handling method======================
                    Set<String> winhandle=driver.getWindowHandles();
               
                    //====================Getting id from all window=============
                    Iterator<String> it=winhandle.iterator();
                    String Parentwin=it.next();
                    String ChildWin=it.next();
                    driver.switchTo().window(ChildWin);
                    driver.findElement(By.xpath("//img[@alt='Ginger Hotel']")).click();
                    Thread.sleep(3000);
                    Set<String> winhandle1=driver.getWindowHandles();
                    Iterator<String> it1=winhandle1.iterator();
                    Parentwin=it1.next();
                    ChildWin=it1.next();
                    String SubChildWin=it1.next();
                    driver.switchTo().window(SubChildWin);
                    driver.findElement(By.cssSelector("#air_fromrowed > a > img")).click();
                    driver.findElement(By.linkText("29")).click();
                    driver.findElement(By.cssSelector("#air_fromrowed1 > a > img")).click();
                    driver.findElement(By.linkText("6")).click();
                    driver.findElement(By.linkText("6")).click();
                    driver.findElement(By.cssSelector("input.grbtn")).click();
                    Thread.sleep(3000);
                  
                    driver.findElement(By.id("roomType0")).click();
                    Select sel=new Select(driver.findElement(By.id("noOfRooms0")));
                    List<WebElement> lst=sel.getOptions();
                    System.out.println(lst.size());
                    for(int i=0;i<lst.size();i++)
                    {
                                  String Roomno=lst.get(i).getText();
                                 if(Roomno.equals("1"))
                                 {
                                     sel.selectByIndex(i);
                                 }
                    }
                    }
}