import java.util.regex.Matcher;
import java.util.regex.Pattern; 

public class JI9059042 {

	public static void main(String[] args) {
		Matcher matcher = Pattern.compile("a").matcher("a"); 
		matcher.find(); 
		matcher.usePattern(Pattern.compile("pattern")); 
		System.out.println(matcher.group()); // returns null 

	}

}