/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.Pattern;
 
/* 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
	{
		Pattern CLEAR_NUMBER_SEQUENCE_PATTERN = Pattern.compile("\\D+", Pattern.CASE_INSENSITIVE);
		String num = "12  3 4   56 7 ";
		String newNum = CLEAR_NUMBER_SEQUENCE_PATTERN.matcher(num).replaceAll("");
		System.out.println(newNum);
	}
}

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