import java.util.*;

public class Compression {
    public static String compress(String input) {
        if (input == null || input.isEmpty()) {
            throw new IllegalArgumentException("Input cannot be null or empty.");
        }
        StringBuilder compressed = new StringBuilder();
        char currentChar = input.charAt(0);
        int count = 1;

        for (int i = 1; i < input.length(); i++) {
            char nextChar = input.charAt(i);
            if (nextChar == currentChar) {
                count++;
            } else {
                compressed.append(currentChar).append("±").append(count);
                currentChar = nextChar;
                count = 1;
            }
        }

        compressed.append(currentChar).append("±").append(count);

        return compressed.toString();
    }

    public static String decompress(String input) {
        if (input == null || input.isEmpty()) {
            throw new IllegalArgumentException("Input cannot be null or empty.");
        }

        StringBuilder decompressed = new StringBuilder();
        String[] tokens = input.split("±");

        if (tokens.length % 2 != 0) {
            throw new IllegalArgumentException("Invalid compressed input.");
        }

        for (int i = 0; i < tokens.length; i += 2) {
            char character = tokens[i].charAt(0);
            int count = Integer.parseInt(tokens[i + 1]);

            if (count < 1) {
                throw new IllegalArgumentException("Invalid compressed count.");
            }

            for (int j = 0; j < count; j++) {
                decompressed.append(character);
            }
        }

        return decompressed.toString();
    }

    public static void main(String[] args) {
        String decompressed = decompress("A±2147483647");
        System.out.println("Decompressed: " + decompressed);
    }
}