[WFA] Nr format cu cifrele maxime din 3 numere

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

namespace aps
{
    public partial class Form1 : Form
    {

        private Int32 cifra(Int32 x)
        {
            int cm = x%10;
            while (x != 0)
            {
                int c = x % 10;
                if (cm < c) cm = c;
                x = x / 10;
            }
            return cm;
        }

        public Form1()
        {
            InitializeComponent();
        }

        private void b_3_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void b_2_Click(object sender, EventArgs e)
        {
            Int32 nr1 = Convert.ToInt32(tb_1.Text);
            Int32 nr2 = Convert.ToInt32(tb_2.Text);
            Int32 nr3 = Convert.ToInt32(tb_3.Text);
            int numar = cifra(nr1) * 100 + cifra(nr2) * 10 + cifra(nr3);

            tb_4.Text = Convert.ToString(numar);
        }

        private void b_1_Click(object sender, EventArgs e)
        {
            tb_1.Text = "";
            tb_2.Text = "";
            tb_3.Text = "";
            tb_4.Text = "";
        }

    }
}