Second Problem

using System;


namespace _2.GSM
{
    class Battery
    {
        //<fields>
        private string model;
        private int hourIdle;
        private int hourTalk;
        //</fields>
        //<constructors>
        public Battery(string model)
        {
            this.model = model;
            this.hourIdle = 0;
            this.hourTalk = 0;
        }

        public Battery(string model, int hourIdle, int hourTalk)
            : this(model)
        {
            this.hourIdle = hourIdle;
            this.hourTalk = hourTalk;
        }
        //</constructors>


    }
    class Display
    {
        //<fields>
        private long colorNums;
        private double width;
        private double height;
        //</fields>

        //<constructors>
        public Display()
        {
            colorNums = 0;
            width = 0;
            height = 0;
        }
        public Display(long colorNum)
            : this()
        {
            this.colorNums = colorNum;

        }
        public Display(long colorNum, double width, double height)
            : this(colorNum)
        {
            this.height = height;
            this.width = width;

        }
        //</constructors>
    }
    class GSM
    {
        //<fields>
        Battery battery;
        Display display;
        private string model;
        private string manufacturer;
        private decimal price;
        private string owner;
        //</fields>

        //<constructors>
        public GSM(string model, string manufacturer)
        {
            this.model = model;
            this.manufacturer = manufacturer;
            price = 0.0m;
            owner = null;

        }
        public GSM(string model, string manufacturer, decimal price)
            : this(model, manufacturer)
        {
            this.price = price;
        }
        public GSM(string model, string manufacturer, decimal price, string owner)
            : this(model, manufacturer,price)
        {

            this.owner = owner;
        }
        //</constructors>

    }
}