import java.util.*;

public class Synchronization {
  public static void main(String[] args) {
    Collection c = 
      Collections.synchronizedCollection(
        new ArrayList());
    List list = Collections.synchronizedList(
      new ArrayList());
    Set s = Collections.synchronizedSet(
      new HashSet());
    Map m = Collections.synchronizedMap(
      new HashMap());
  }
} ///:~