public class Account {
    private int _balance;
    private static int _funds = 0;

    public Account(int balance0) {
        if (balance0 < 0) {
            throw new IllegalArgumentException("negative deposit");
        }
        _balance = balance0;
        _funds = balance0;
    }

    public int balance() {
        return _balance;
    }

    public static int funds() {
        return _funds;
    }

    public int deposit(int amount) {
        if (amount < 0) {
            throw new IllegalArgumentException("negative deposit");
        }
        _funds += amount;
        _balance += amount;
        return _balance;
    }

    public int withdraw(int amount) {
        if (_balance < amount)
            throw new IllegalStateException("Insufficient funds");
        _funds -= amount;
        _balance -= amount;
        return _balance;
    }
}