Implement a single bank account that processes deposits and withdrawals from a command stream, rejecting withdrawals that would overdraw it.
Implement a single bank account. The balance starts at 0. Process commands from stdin, one per line.
Commands:
- DEPOSIT <amount> : add <amount> to the balance. Print "OK <balance>" with the new balance.
- WITHDRAW <amount> : if the account has at least <amount>, subtract it and print "OK <balance>". Otherwise reject the withdrawal (the balance does not change) and print "DENIED <balance>".
- BALANCE : print "BALANCE <balance>" with the current balance.
All amounts are positive integers. The account can never go negative; a withdrawal larger than the current balance is denied and leaves the balance unchanged.