/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.Matcher;
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) {
        System.out.println(mainMethod("When I was younger So much younger Than "+
        "today Информацию из файла в верхний регистр"));
    }
 
    public static String mainMethod(String input) {
        Pattern p = Pattern.compile("(\\w{4,}+|[А-Яа-яёЁ]{4,}+)");
        Matcher m = p.matcher(input);
        StringBuffer sb = new StringBuffer(input.length());
        while (m.find()) {
            char[] chars = m.group(1).toCharArray();
            for (int i = 0; i < chars.length; i++) {
                char c = chars[i];
                if (Character.isUpperCase(c)) {
                    chars[i] = Character.toLowerCase(c);
                } else {
                    chars[i] = Character.toUpperCase(c);
                }
            }
            m.appendReplacement(sb, String.valueOf(chars));
        }
        m.appendTail(sb);
        return sb.toString();
    }
}

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