import java.io.*;

import java.util.regex.*;

/**

This class demonstrates how to read a line of text from the keyboard

Based on http://www.abbeyworkshop.com/howto/java/readLine/ReadLine.java

*/

public class Grep{

public static void main(String[] args){

try {

Pattern pattern = Pattern.compile(args[0]);

String line = "";

InputStreamReader converter = new InputStreamReader(System.in);

BufferedReader in = new BufferedReader(converter);

line = in.readLine();

while (line != null){

Matcher matcher = pattern.matcher(line);

if(matcher.find()) {

System.out.println(line);

}

line = in.readLine();

}

}catch (IOException e){

System.out.println("IO Exception\n");

}catch (ArrayIndexOutOfBoundsException e){

System.out.println("Usage: java Grep REGEX (and then type strings on STDIN, Ctr-D to exit)\n");

}

}

}