namespace App3
{
    [Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
    public class MainActivity : AppCompatActivity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.activity_main);
            Button submit = FindViewById<Button>
(Resource.Id.btnSubmit);
            submit.Click += delegate
            {
                var userPostno = FindViewById<EditText>
(Resource.Id.postnoValue);
                string userValue = userPostno.Text.ToString();
                var showResult = FindViewById<TextView>
(Resource.Id.postnoResult);
                if (userValue == "00100")
                {
                    showResult.Text = "S1";
                }
                else
                {
                    showResult.Text = "POSTI";
                }