import javax.swing.JOptionPane;


public class Demo1
{
	public static void main(String[] args)
	{
		String strNum = JOptionPane.showInputDialog("How many students?");
		int num = Integer.parseInt(strNum);
		int sum = 0;
		for(int i=0; i<num;i++)
		{
			String strMark = JOptionPane.showInputDialog("mark"+(i+1));
			int mark = Integer.parseInt(strMark);
			sum= sum + mark;
		}
		JOptionPane.showMessageDialog(null, "ave="+sum/(double)num);
	}
}