using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Text;
using System.Windows.Forms;
public class Form1 : Form {
protected override void OnPaint(PaintEventArgs e) {
Graphics g = e.Graphics;
g.FillRectangle(Brushes.White, this.ClientRectangle);
Rectangle rect = new Rectangle(10, 10, 80, 50);
g.DrawRectangle(Pens.Black, rect);
g.SetClip(rect);
g.FillEllipse(Brushes.Blue, 20, 20, 100, 100);
}
public static void Main() {
Application.Run(new Form1());
}
}