import java.util.*;
public class FunWithGenerics
{
	//note that Integer extends Number
	public static void f0(Collection<Comparable> a){}
	public static <A> void f1(Collection<A> a){}
	public static void f2(Collection<? extends Number> arr){}
	public static void f3(Collection<? super Number> arr){}
	public static <A extends Comparable<? super A>> void f4(Collection<A> a){}

	public static void main(String[] args)
	{
		/*
		//when uncommented, which of the following calls will be valid?
		Collection<Comparable> comCol=new ArrayList<Comparable>();
		f0(comCol);
		f1(comCol);
		f2(comCol);
		f3(comCol);
		f4(comCol);
		*/
		
		/*
		Collection<Object> objCol=new ArrayList<Object>();
		f0(objCol);
		f1(objCol);
		f2(objCol);
		f3(objCol);
		f4(objCol);
		*/
		
		/*
		Collection<Number> numCol=new ArrayList<Number>();
		f0(numCol);
		f1(numCol);
		f2(numCol);
		f3(numCol);
		f4(numCol);
		*/
		
		/*
		Collection<Integer> intCol=new ArrayList<Integer>();
		f0(intCol);
		f1(intCol);
		f2(intCol);
		f3(intCol);
		f4(intCol);
		*/

		/*
		Collection<String> strCol=new ArrayList<String>();
		f0(strCol);
		f1(strCol);
		f2(strCol);
		f3(strCol);
		f4(strCol);
		*/
	}
}