private void DgvMedicine_CellClick(object sender, DataGridViewCellEventArgs e)
{
btnUpdate.Visible = true;
btnCreate.Visible = false;
int id = (int)dgvMedicine.Rows[e.RowIndex].Cells[0].Value;
ID = id;
Medicine medicine = _pharmacy.GetMedicine(id);
txtMedicine.Text = medicine.Name;
txtPrice.Text = medicine.Price;
}