using System;
using System.Collections;

public class BankAccount {

   private double interestRate;
   private string owner;
   private decimal balance;
   private long accountNumber;

   private static long nextAccountNumber = 0;
   private static ArrayList accounts = new ArrayList();

   public BankAccount(string owner): this(owner, 0.0) {
   }

   public BankAccount(string owner, double interestRate) {
      nextAccountNumber++;
      accounts.Add(this);
      this.accountNumber = nextAccountNumber;
      this.interestRate = interestRate;
      this.owner = owner; 
      this.balance = 0.0M;
   }   

   public override bool Equals(Object obj){
     if (obj == null)
       return false;
     else if (this.GetType() != obj.GetType())
       return false;
     else if (ReferenceEquals(this, obj))
       return true;
     else if (this.accountNumber == ((BankAccount)obj).accountNumber)
       return true;
     else return false;
   }

   public override int GetHashCode(){
     return (int)accountNumber ^ (int)(accountNumber >> 32);
     // XOR of low orders and high orders bits of accountNumber
     // (of type long) according to GetHashCode API recommendation.
   }

   public decimal Balance () {
      return balance;
   }

   public static long NumberOfAccounts (){
     return nextAccountNumber;
   }

   public static BankAccount GetAccount (long accountNumber){
      foreach(BankAccount ba in accounts)
        if (ba.accountNumber == accountNumber)
           return ba;
      return null;
   }

   public void Withdraw (decimal amount) {
      balance -= amount;
   }

   public void Deposit (decimal amount) {
      balance += amount;
   }

   public void AddInterests() {
      balance = balance + balance * (decimal)interestRate;
   }    

   public override string ToString() {
      return owner + "'s account, no. " + accountNumber + " holds " +
            + balance + " kroner";
   }
}