public class MainClass {
public static void main(String[] args) {
StringBuffer sb1 = new StringBuffer("xy");
System.out.println(sb1);
sb1.insert(0, false);
System.out.println(sb1);
StringBuffer sb2 = new StringBuffer("xy");
System.out.println(sb2);
sb2.insert(1, true);
System.out.println(sb2);
}
}