import java.util.*; import java.util.zip.*; import java.util.List; import java.util.regex.*; import java.util.concurrent.*; import java.util.concurrent.atomic.*; import java.util.concurrent.locks.*; import java.util.function.*; import javax.swing.*; import javax.swing.event.*; import javax.swing.text.*; import javax.swing.table.*; import java.io.*; import java.net.*; import java.lang.reflect.*; import java.lang.ref.*; import java.lang.management.*; import java.security.*; import java.security.spec.*; import java.awt.*; import java.awt.event.*; import java.awt.image.*; import java.awt.geom.*; import javax.imageio.*; import java.math.*; import java.time.Duration; import java.lang.invoke.VarHandle; import java.lang.invoke.MethodHandles; class main { static A elementBefore(Collection l, A a) { A last = null; if (l != null) for (var b : l) { if (eq(a, b)) return last; last = b; } return null; } static boolean eq(Object a, Object b) { return a == b || a != null && b != null && a.equals(b); } static String str(Object o) { return o == null ? "null" : o.toString(); } static String str(char[] c) { return new String(c); } static String str(char[] c, int offset, int count) { return new String(c, offset, count); } }