class ClassA<T> {
	public T t;
}

class Samp06 {
	public static void main(String[] args){
		ClassA<?> ca1 = new ClassA<Integer>();
		ClassA ca2 = new ClassA<Integer>();
		ClassA<Integer> ca3;
		ca3 = ca1; // ERROR
		ca3 = ca2; // WARNING
		ca1 = ca2; // OK
		ca2 = ca1; // OK
	}
}