/*
 * Using regular expressions in Java
 * 
 * Example program from Adam Brooks Weber,
 *                      Formal Language: A Practical Introduction,
 *                      pages 96-97
 *                      
 * With additional comments added by Bill Slough
 * 
 * See:
 *     http://download.oracle.com/javase/tutorial/essential/regex/
 * 
 * for many more details of regular expressions in Java.
 */

import java.io.*;
import java.util.regex.*;

public class RegexFilter {

    public static void main(String[] args) throws IOException {

        // Get a regular expression from the command line argument
        Pattern p = Pattern.compile(args[0]);

        // Obtain input from standard input
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

        // Process the input file, one line at a time
        String s = in.readLine();   // get the next line, if possible
        
        while (s != null) {
            // Create a matcher that builds an NFA for the given pattern p
            Matcher m = p.matcher(s);

            // Echo the input line if it matches the regular expression
            if (m.matches()) {
                System.out.println(s);
            }

            s = in.readLine();  // get the next line
        }

    }
}