/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.*;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
    	System.out.println(regexMatcher("String 551i", "-?(?>\\d*\\.?\\d+)(?!i)"));
	}
	private static double regexMatcher(String s, String regex) {
	    Pattern pattern = Pattern.compile(regex);
	    Matcher matcher = pattern.matcher(s.replaceAll("\\s+", ""));
 
	    if (!matcher.find()) {
	        return 0;
	    }
	    String found = matcher.group();
 
	    return Double.parseDouble(matcher.group());
	}
}

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