private void button3_Click(object sender, EventArgs e)
{
string city = (string)citiesList.SelectedItem;
string station = (string)stationsList.SelectedItem;
Stopwatch stopwatch = Stopwatch.StartNew();
int availableBikes = client.GetAvailableBikesForStation(station, city);
stopwatch.Stop();
label5.Text = "Execution time of GetAvailableBikes: " + stopwatch.ElapsedMilliseconds + "ms";
label5.Visible = true;
label1.Text = "Available bikes: " + availableBikes;
label1.Visible = true;
}