contract Ownable {
    address public owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor() public {
        owner = msg.sender;
    }

    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address newOwner) public onlyOwner {
        require(newOwner != address(0));
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }

}

contract Pausable is Ownable {
    event Pause();
    event Unpause();

    bool public paused = false;

    modifier whenNotPaused() {
        if (msg.sender != owner) {
            require(!paused);
        }
        _;
    }

    modifier whenPaused() {
        if (msg.sender != owner) {
            require(paused);
        }
        _;
    }

    function pause() onlyOwner public {
        paused = true;
        emit Pause();
    }

    function unpause() onlyOwner public {
        paused = false;
        emit Unpause();
    }
}

library SafeMath {
    function mul(uint a, uint b) internal pure returns (uint) {
        if (a == 0) {
            return 0;
        }
        uint c = a * b;
        assert(c / a == b);
        return c;
    }

    function div(uint a, uint b) internal pure returns (uint) {
        // assert(b > 0); // Solidity automatically throws when dividing by 0
        uint c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
        return c;
    }

    function sub(uint a, uint b) internal pure returns (uint) {
        assert(b <= a);
        return a - b;
    }

    function add(uint a, uint b) internal pure returns (uint) {
        uint c = a + b;
        assert(c >= a);
        return c;
    }
}

contract ERC20 {
    string public name;
    string public symbol;
    uint8 public decimals;
    uint public totalSupply;
    constructor(string _name, string _symbol, uint8 _decimals) public {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;
    }
    function balanceOf(address who) public view returns (uint);
    function transfer(address to, uint value) public returns (bool);
    function allowance(address owner, address spender) public view returns (uint);
    function transferFrom(address from, address to, uint value) public returns (bool);
    function approve(address spender, uint value) public returns (bool);
    event Transfer(address indexed from, address indexed to, uint value);
    event Approval(address indexed owner, address indexed spender, uint value);
}

contract Token is Pausable, ERC20 {
    using SafeMath for uint;
    event Burn(address indexed burner, uint256 value);

    mapping(address => uint) balances;
    mapping (address => mapping (address => uint)) internal allowed;
    mapping(address => uint) public balanceOfLocked;
    mapping(address => bool) public addressLocked;

    constructor() ERC20("DWS", "DWS", 18) public {
        totalSupply = 500000000 * 10 ** uint(decimals);
        balances[msg.sender] = totalSupply;
    }

    modifier lockCheck(address from, uint value) { 
        require(addressLocked[from] == false);
        require(balances[from] >= balanceOfLocked[from]);
        require(value <= balances[from] - balanceOfLocked[from]);
        _;
    }

    function burn(uint _value) onlyOwner public {
        balances[owner] = balances[owner].sub(_value);
        totalSupply = totalSupply.sub(_value);
        emit Burn(msg.sender, _value);
    }

    function lockAddressValue(address _addr, uint _value) onlyOwner public {
        balanceOfLocked[_addr] = _value;
    }

    function lockAddress(address addr) onlyOwner public {
        addressLocked[addr] = true;
    }

    function unlockAddress(address addr) onlyOwner public {
        addressLocked[addr] = false;
    }

    function transfer(address _to, uint _value) lockCheck(msg.sender, _value) whenNotPaused public returns (bool) {
        require(_to != address(0));
        require(_value <= balances[msg.sender]);

        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    function balanceOf(address _owner) public view returns (uint balance) {
        return balances[_owner];
    }

    function transferFrom(address _from, address _to, uint _value) public lockCheck(_from, _value) whenNotPaused returns (bool) {
        require(_to != address(0));
        require(_value <= balances[_from]);
        require(_value <= allowed[_from][msg.sender]);

        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        emit Transfer(_from, _to, _value);
        return true;
    }

    function approve(address _spender, uint _value) public whenNotPaused returns (bool) {
        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) public view returns (uint) {
        return allowed[_owner][_spender];
    }

    function increaseApproval(address _spender, uint _addedValue) public whenNotPaused returns (bool) {
        allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
        emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

    function decreaseApproval(address _spender, uint _subtractedValue) public whenNotPaused returns (bool) {
        uint oldValue = allowed[msg.sender][_spender];
        if (_subtractedValue > oldValue) {
            allowed[msg.sender][_spender] = 0;
        } else {
            allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }
        emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }
}