private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    this.panel1.Controls.Clear();
    int weith = 200;
    int high = 200;
    int interval = Convert.ToInt32(this.numericUpDown1.Value);
    int pointX = this.panel1.Width / 2 - (weith + interval) * Convert.ToInt32(this.comboBox1.Text) / 2;
    int pointY = this.panel1.Height / 2 - (high + interval) / 2;
    for (int i = 0; i < Convert.ToInt32(this.comboBox1.Text); i++)
    {
        PictureBox pic = new PictureBox();
        string path = AppDomain.CurrentDomain.BaseDirectory + "hj.jpg";
        pic.Image = Image.FromFile(path);
        pic.SizeMode = PictureBoxSizeMode.CenterImage;
        pic.Size = new Size(weith, high);
        pic.Location = new Point(pointX, pointY);
        this.panel1.Controls.Add(pic);
        pointX += weith + interval;
    }
}