using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Numerics;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication5
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            String str = textBox1.Text.Replace(" ", "").Trim();

            if (str.Length != 24) {
                textBox1.Text = "Podaj poprawny kod";
                return;
            }

            str = str + "252100";
            int mod = 0;
            foreach(var num in str)
                mod = (10 * mod + int.Parse(num.ToString())) % 97;
            mod = 98 - mod;

            textBox2.Text = "PL" + mod +" "+ textBox1.Text;

        }

        private void button2_Click(object sender, EventArgs e)
        {
            String str = textBox2.Text.Replace(" ", "").Trim();

            if (str.Length != 28)
            {
                textBox2.Text = "Podaj poprawny kod";
                return;
            }

            String code = str.Substring(0,4);
            code = code.Replace("PL","2521");
            str = str.Remove(0,4) + code;

            int mod = 0;
            foreach (var num in str)
                mod = (10 * mod + int.Parse(num.ToString())) % 97;

            if (mod == 1){
                label2.Text = "Poprawny";
            }
            else {
                label2.Text = "Niepoprawny";
            }

        }
    }
}