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 File dirOtherwiseNull(File dir) {
  return isDirectory(dir) ? dir : null;
}
static boolean isDirectory(File f) {
  return f != null && f.isDirectory();
}

static boolean isDirectory(String path) {
  return path != null && isDirectory(newFile(path));
}



static File newFile(File base, String... names) {
  for (String name : names) base = new File(base, name);
  return base;
}

static File newFile(String name) {
  return name == null ? null : new File(name);
}

static File newFile(String base, String... names) {
  return newFile(newFile(base), names);
}


}