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 <A, B> A firstKeyWithValue(Map<A, B> map, B value) {
  if (map != null) for (Map.Entry<A, B> e : map.entrySet())
    if (eq(e.getValue(), value))
      return e.getKey();
  return null;
}

static <A, B> A firstKeyWithValue(B value, Map<A, B> map) {
  return firstKeyWithValue(map, value);
}
static boolean eq(Object a, Object b) {
  return a == null ? b == null : a == b || 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);
}

}