dotv1

/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.Pattern;
import java.util.regex.Matcher;


/* 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 pattern = Pattern.compile("(\\d)(\\d{3})");
        Matcher matcher = pattern.matcher("sanyi1234 12345678910 másiksanyi12 142857142");
        System.out.println( matcher.replaceAll("$1.$2") );
    }
}