1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication4
{
    abstract class Coin
    {
        public double Value { get; private set; }
        protected Coin(double value)
        {
            this.Value = value;
        }
        public abstract double Convert();
    }
    class cent : Coin
    {
        public cent(double val)
            : base(val)
        {
        }
        public override double Convert()
        {
            return base.Value * 30;
        }
        public abstract class Program
        {
            static cent sum(Coin  c1, Coin c2)
            {
                int ans = c1.Value+c2.Value;
                return ans;
            }

            static void Main(string[] args)
            {
                Coin c1 = new cent(50.1);
                Coin c2 = new cent(20);
                Coin c = sum(c1, c2);
                Console.WriteLine(c);
            }
        }
    }
}