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 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 javax.imageio.*;
import java.math.*;
class main {
static void test_substring() {
assertEqualsVerbose(substring("abc", 2, 4), "c");
assertEqualsVerbose(substring("abc", -3, 1), "a");
assertEqualsVerbose(substring("abc", 2, 1), "");
}
static A assertEqualsVerbose(Object x, A y) {
assertEqualsVerbose((String) null, x, y);
return y;
}
// x = expected, y = actual
static A assertEqualsVerbose(String msg, Object x, A y) {
if (!eq(x, y)) {
throw fail((msg != null ? msg + ": " : "") + "expected: "+ x + ", got: " + y);
} else
print("OK" + (empty(msg) ? "" : " " + msg) + ": " + /*sfu*/(x));
return y;
}
static String substring(String s, int x) {
return substring(s, x, strL(s));
}
static String substring(String s, int x, int y) {
if (s == null) return null;
if (x < 0) x = 0;
int n = s.length();
if (y < x) y = x;
if (y > n) y = n;
if (x >= y) return "";
return s.substring(x, y);
}
// convenience method for quickly dropping a prefix
static String substring(String s, CharSequence l) {
return substring(s, l(l));
}
static boolean eq(Object a, Object b) {
return a == b || a != null && b != null && a.equals(b);
}
static RuntimeException fail() { throw new RuntimeException("fail"); }
static RuntimeException fail(Throwable e) { throw asRuntimeException(e); }
static RuntimeException fail(Object msg) { throw new RuntimeException(String.valueOf(msg)); }
static RuntimeException fail(String msg) { throw new RuntimeException(msg == null ? "" : msg); }
static RuntimeException fail(String msg, Throwable innerException) { throw new RuntimeException(msg, innerException); }
static volatile StringBuffer local_log = new StringBuffer(); // not redirected
static volatile Appendable print_log = local_log; // might be redirected, e.g. to main bot
// in bytes - will cut to half that
static volatile int print_log_max = 1024*1024;
static volatile int local_log_max = 100*1024;
static boolean print_silent = false; // total mute if set
static Object print_byThread_lock = new Object();
static volatile ThreadLocal