class BankingSystemLevel3:
    def __init__(self):
        self.accounts = {}
        self.transfers = {}
        self.transfer_counter = 1
        self.transfer_expiry = 86400000  # 24 hours in milliseconds

    def create_account(self, timestamp, account_id):
        if account_id in self.accounts:
            return "false"
        self.accounts[account_id] = 0
        return "true"

    def deposit(self, timestamp, account_id, amount):
        if account_id not in self.accounts:
            return ""
        self.accounts[account_id] += int(amount)
        return str(self.accounts[account_id])

    def pay(self, timestamp, account_id, amount):
        if account_id not in self.accounts or self.accounts[account_id] < int(amount):
            return ""
        self.accounts[account_id] -= int(amount)
        return str(self.accounts[account_id])

    def transfer(self, timestamp, source_account_id, target_account_id, amount):
        if source_account_id == target_account_id or \
                source_account_id not in self.accounts or \
                target_account_id not in self.accounts or \
                self.accounts[source_account_id] < int(amount):
            return ""

        transfer_id = f"transfer{self.transfer_counter}"
        self.transfer_counter += 1

        # Withdraw the amount from source account
        self.accounts[source_account_id] -= int(amount)

        # Create a transfer
        self.transfers[transfer_id] = {
            'source': source_account_id,
            'target': target_account_id,
            'amount': int(amount),
            'timestamp': int(timestamp),
            'expired': False
        }
        return transfer_id

    def accept_transfer(self, timestamp, account_id, transfer_id):
        if transfer_id not in self.transfers or \
                self.transfers[transfer_id]['target'] != account_id or \
                self.transfers[transfer_id]['expired']:
            return "false"

        # Check for expiry
        if int(timestamp) - self.transfers[transfer_id]['timestamp'] > self.transfer_expiry:
            self.accounts[self.transfers[transfer_id]['source']] += self.transfers[transfer_id]['amount']
            self.transfers[transfer_id]['expired'] = True
            return "false"

        # Complete transfer
        self.accounts[account_id] += self.transfers[transfer_id]['amount']
        del self.transfers[transfer_id]  # Remove transfer as it is completed
        return "true"

    def process_queries(self, queries):
        results = []
        for query in queries:
            operation = query[0]
            args = query[1:]
            if operation == "CREATE_ACCOUNT":
                results.append(self.create_account(*args))
            elif operation == "DEPOSIT":
                results.append(self.deposit(*args))
            elif operation == "PAY":
                results.append(self.pay(*args))
            elif operation == "TRANSFER":
                results.append(self.transfer(*args))
            elif operation == "ACCEPT_TRANSFER":
                results.append(self.accept_transfer(*args))
        return results

# Example usage:
banking_system = BankingSystemLevel3()
queries = [
    ["CREATE_ACCOUNT", "1622534400000", "account1"],
    ["CREATE_ACCOUNT", "1622534401000", "account2"],
    ["DEPOSIT", "1622534402000", "account1", "1000"],
    ["DEPOSIT", "1622534403000", "account2", "1000"],
    ["TRANSFER", "1622534404000", "account1", "account2", "500"],
    ["ACCEPT_TRANSFER", "1622620800000", "account2", "transfer1"],
    ["TRANSFER", "1622534405000", "account1", "account2", "100"],
    ["ACCEPT_TRANSFER", "1622620801000", "account2", "transfer2"]
]

# Process the queries and output the results
output = banking_system.process_queries(queries)
output