import java.util.*;
class Main {
  public static void main (String[] args) {
     List<Boolean> l = new ArrayList<Boolean>();
     l.add(true);
     l.add(true);
     l.add(null);
     l.add(true);
     int c = 0;
     for(Iterator<Boolean> it = l.iterator(); it.hasNext();) {
         if(it.next()) {
             System.out.println(c);
         }
         c++;
     }
  }
}