/* 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
	{
		String s = "Вася сегодня съел 123456 яблок";
		String regex = "\\b\\d{4,7}\\b";
		Pattern pattern = Pattern.compile(regex);
		Matcher matcher = pattern.matcher(s);
		while (matcher.find()){
			System.out.println(matcher.group(0)); 
		} 
	}
}

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