import java.io.File;
import java.io.FileNotFoundException;
import java.util.Arrays;
import java.util.Scanner;

public class ExtractMessage {

    public static void main(String[] args) throws FileNotFoundException {
        Scanner in = new Scanner(System.in);
        int[] fileData = null;
        do {
            System.out.println("Please enter the file name: ");
            String fileName = in.nextLine();
            fileData = getCodes(fileName);
        } while (fileData == null);
        in.close();
        System.out.println("The secret message was: " + getSecretMessage(fileData));
    }

    private static int[] getCodes(String filename) throws FileNotFoundException {
        File file = new File(filename);
        if (!file.exists()) {
            System.out.println("File does not exist.");
            return null;
        }
        Scanner input = new Scanner(file);
        int[] codes = null;
        while (input.hasNext()) {
            if (input.hasNextInt()) {
                int num = input.nextInt();
                if (codes == null) {
                    codes = new int[1];
                    codes[0] = num;
                } else {
                    codes = Arrays.copyOf(codes, codes.length + 1);
                    codes[codes.length - 1] = num;
                }
            } else {
                input.next();
            }
        }
        return codes;
    }

    private static String getSecretMessage(int[] codes) {
        String msg = "";
        for (int i = 0; i < codes.length; i++) {
            msg += (char)(codes[i] - codes.length);
        }
        return msg;
    }

}