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

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

   public decimal Balance () {
      return this.balance;
   }

   public static long NumberOfAccounts (){
     return BankAccount.nextAccountNumber;
   }

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

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

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

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

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