// Vulnerability label: IOU1
pragma solidity ^0.4.24;

// File: openzeppelin-solidity/contracts/math/SafeMath.sol

/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, reverts on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    uint256 c = a * b;
    require(c / a == b);

    return c;
  }

  /**
  * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0); // Solidity only automatically asserts when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold

    return c;
  }

  /**
  * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    uint256 c = a - b;

    return c;
  }

  /**
  * @dev Adds two numbers, reverts on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a);

    return c;
  }

  /**
  * @dev Divides two numbers and returns the remainder (unsigned integer modulo),
  * reverts when dividing by zero.
  */
  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0);
    return a % b;
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/IERC20.sol

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
interface IERC20 {
  function totalSupply() external view returns (uint256);

  function balanceOf(address who) external view returns (uint256);

  function allowance(address owner, address spender)
    external view returns (uint256);

  function transfer(address to, uint256 value) external returns (bool);

  function approve(address spender, uint256 value)
    external returns (bool);

  function transferFrom(address from, address to, uint256 value)
    external returns (bool);

  event Transfer(
    address indexed from,
    address indexed to,
    uint256 value
  );

  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}

// File: openzeppelin-solidity/contracts/token/ERC20/SafeERC20.sol

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure.
 * To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {

  using SafeMath for uint256;

  function safeTransfer(
    IERC20 token,
    address to,
    uint256 value
  )
    internal
  {
    require(token.transfer(to, value));
  }

  function safeTransferFrom(
    IERC20 token,
    address from,
    address to,
    uint256 value
  )
    internal
  {
    require(token.transferFrom(from, to, value));
  }

  function safeApprove(
    IERC20 token,
    address spender,
    uint256 value
  )
    internal
  {
    // safeApprove should only be called when setting an initial allowance, 
    // or when resetting it to zero. To increase and decrease it, use 
    // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
    require((value == 0) || (token.allowance(msg.sender, spender) == 0));
    require(token.approve(spender, value));
  }

  function safeIncreaseAllowance(
    IERC20 token,
    address spender,
    uint256 value
  )
    internal
  {
    uint256 newAllowance = token.allowance(address(this), spender).add(value);
    require(token.approve(spender, newAllowance));
  }

  function safeDecreaseAllowance(
    IERC20 token,
    address spender,
    uint256 value
  )
    internal
  {
    uint256 newAllowance = token.allowance(address(this), spender).sub(value);
    require(token.approve(spender, newAllowance));
  }
}

// File: openzeppelin-solidity/contracts/utils/ReentrancyGuard.sol

/**
 * @title Helps contracts guard against reentrancy attacks.
 * @author Remco Bloemen <remco@2π.com>, Eenae <alexey@mixbytes.io>
 * @dev If you mark a function `nonReentrant`, you should also
 * mark it `external`.
 */
contract ReentrancyGuard {

  /// @dev counter to allow mutex lock with only one SSTORE operation
  uint256 private _guardCounter;

  constructor() internal {
    // The counter starts at one to prevent changing it from zero to a non-zero
    // value, which is a more expensive operation.
    _guardCounter = 1;
  }

  /**
   * @dev Prevents a contract from calling itself, directly or indirectly.
   * Calling a `nonReentrant` function from another `nonReentrant`
   * function is not supported. It is possible to prevent this from happening
   * by making the `nonReentrant` function external, and make it call a
   * `private` function that does the actual work.
   */
  modifier nonReentrant() {
    _guardCounter += 1;
    uint256 localCounter = _guardCounter;
    _;
    require(localCounter == _guardCounter);
  }

}

// File: openzeppelin-solidity/contracts/crowdsale/Crowdsale.sol

/**
 * @title Crowdsale
 * @dev Crowdsale is a base contract for managing a token crowdsale,
 * allowing investors to purchase tokens with ether. This contract implements
 * such functionality in its most fundamental form and can be extended to provide additional
 * functionality and/or custom behavior.
 * The external interface represents the basic interface for purchasing tokens, and conform
 * the base architecture for crowdsales. They are *not* intended to be modified / overridden.
 * The internal interface conforms the extensible and modifiable surface of crowdsales. Override
 * the methods to add functionality. Consider using 'super' where appropriate to concatenate
 * behavior.
 */
contract Crowdsale is ReentrancyGuard {
  using SafeMath for uint256;
  using SafeERC20 for IERC20;

  // The token being sold
  IERC20 private _token;

  // Address where funds are collected
  address private _wallet;

  // How many token units a buyer gets per wei.
  // The rate is the conversion between wei and the smallest and indivisible token unit.
  // So, if you are using a rate of 1 with a ERC20Detailed token with 3 decimals called TOK
  // 1 wei will give you 1 unit, or 0.001 TOK.
  uint256 private _rate;

  // Amount of wei raised
  uint256 private _weiRaised;

  /**
   * Event for token purchase logging
   * @param purchaser who paid for the tokens
   * @param beneficiary who got the tokens
   * @param value weis paid for purchase
   * @param amount amount of tokens purchased
   */
  event TokensPurchased(
    address indexed purchaser,
    address indexed beneficiary,
    uint256 value,
    uint256 amount
  );

  /**
   * @param rate Number of token units a buyer gets per wei
   * @dev The rate is the conversion between wei and the smallest and indivisible
   * token unit. So, if you are using a rate of 1 with a ERC20Detailed token
   * with 3 decimals called TOK, 1 wei will give you 1 unit, or 0.001 TOK.
   * @param wallet Address where collected funds will be forwarded to
   * @param token Address of the token being sold
   */
  constructor(uint256 rate, address wallet, IERC20 token) internal {
    require(rate > 0);
    require(wallet != address(0));
    require(token != address(0));

    _rate = rate;
    _wallet = wallet;
    _token = token;
  }

  // -----------------------------------------
  // Crowdsale external interface
  // -----------------------------------------

  /**
   * @dev fallback function ***DO NOT OVERRIDE***
   * Note that other contracts will transfer fund with a base gas stipend
   * of 2300, which is not enough to call buyTokens. Consider calling
   * buyTokens directly when purchasing tokens from a contract.
   */
  function () external payable {
    buyTokens(msg.sender);
  }

  /**
   * @return the token being sold.
   */
  function token() public view returns(IERC20) {
    return _token;
  }

  /**
   * @return the address where funds are collected.
   */
  function wallet() public view returns(address) {
    return _wallet;
  }

  /**
   * @return the number of token units a buyer gets per wei.
   */
  function rate() public view returns(uint256) {
    return _rate;
  }

  /**
   * @return the amount of wei raised.
   */
  function weiRaised() public view returns (uint256) {
    return _weiRaised;
  }

  /**
   * @dev low level token purchase ***DO NOT OVERRIDE***
   * This function has a non-reentrancy guard, so it shouldn't be called by
   * another `nonReentrant` function.
   * @param beneficiary Recipient of the token purchase
   */
  function buyTokens(address beneficiary) public nonReentrant payable {

    uint256 weiAmount = msg.value;
    _preValidatePurchase(beneficiary, weiAmount);

    // calculate token amount to be created
    uint256 tokens = _getTokenAmount(weiAmount);

    // update state
    _weiRaised = _weiRaised.add(weiAmount);

    _processPurchase(beneficiary, tokens);
    emit TokensPurchased(
      msg.sender,
      beneficiary,
      weiAmount,
      tokens
    );

    _updatePurchasingState(beneficiary, weiAmount);

    _forwardFunds();
    _postValidatePurchase(beneficiary, weiAmount);
  }

  // -----------------------------------------
  // Internal interface (extensible)
  // -----------------------------------------

  /**
   * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met. Use `super` in contracts that inherit from Crowdsale to extend their validations.
   * Example from CappedCrowdsale.sol's _preValidatePurchase method:
   *   super._preValidatePurchase(beneficiary, weiAmount);
   *   require(weiRaised().add(weiAmount) <= cap);
   * @param beneficiary Address performing the token purchase
   * @param weiAmount Value in wei involved in the purchase
   */
  function _preValidatePurchase(
    address beneficiary,
    uint256 weiAmount
  )
    internal
    view
  {
    require(beneficiary != address(0));
    require(weiAmount != 0);
  }

  /**
   * @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid conditions are not met.
   * @param beneficiary Address performing the token purchase
   * @param weiAmount Value in wei involved in the purchase
   */
  function _postValidatePurchase(
    address beneficiary,
    uint256 weiAmount
  )
    internal
    view
  {
    // optional override
  }

  /**
   * @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends its tokens.
   * @param beneficiary Address performing the token purchase
   * @param tokenAmount Number of tokens to be emitted
   */
  function _deliverTokens(
    address beneficiary,
    uint256 tokenAmount
  )
    internal
  {
    _token.safeTransfer(beneficiary, tokenAmount);
  }

  /**
   * @dev Executed when a purchase has been validated and is ready to be executed. Doesn't necessarily emit/send tokens.
   * @param beneficiary Address receiving the tokens
   * @param tokenAmount Number of tokens to be purchased
   */
  function _processPurchase(
    address beneficiary,
    uint256 tokenAmount
  )
    internal
  {
    _deliverTokens(beneficiary, tokenAmount);
  }

  /**
   * @dev Override for extensions that require an internal state to check for validity (current user contributions, etc.)
   * @param beneficiary Address receiving the tokens
   * @param weiAmount Value in wei involved in the purchase
   */
  function _updatePurchasingState(
    address beneficiary,
    uint256 weiAmount
  )
    internal
  {
    // optional override
  }

  /**
   * @dev Override to extend the way in which ether is converted to tokens.
   * @param weiAmount Value in wei to be converted into tokens
   * @return Number of tokens that can be purchased with the specified _weiAmount
   */
  function _getTokenAmount(uint256 weiAmount)
    internal view returns (uint256)
  {
    return weiAmount.mul(_rate);
  }

  /**
   * @dev Determines how ETH is stored/forwarded on purchases.
   */
  function _forwardFunds() internal {
    _wallet.transfer(msg.value);
  }
}

// File: openzeppelin-solidity/contracts/crowdsale/validation/CappedCrowdsale.sol

/**
 * @title CappedCrowdsale
 * @dev Crowdsale with a limit for total contributions.
 */
contract CappedCrowdsale is Crowdsale {
  using SafeMath for uint256;

  uint256 private _cap;

  /**
   * @dev Constructor, takes maximum amount of wei accepted in the crowdsale.
   * @param cap Max amount of wei to be contributed
   */
  constructor(uint256 cap) internal {
    require(cap > 0);
    _cap = cap;
  }

  /**
   * @return the cap of the crowdsale.
   */
  function cap() public view returns(uint256) {
    return _cap;
  }

  /**
   * @dev Checks whether the cap has been reached.
   * @return Whether the cap was reached
   */
  function capReached() public view returns (bool) {
    return weiRaised() >= _cap;
  }

  /**
   * @dev Extend parent behavior requiring purchase to respect the funding cap.
   * @param beneficiary Token purchaser
   * @param weiAmount Amount of wei contributed
   */
  function _preValidatePurchase(
    address beneficiary,
    uint256 weiAmount
  )
    internal
    view
  {
    super._preValidatePurchase(beneficiary, weiAmount);
    require(weiRaised().add(weiAmount) <= _cap);
  }

}

// File: openzeppelin-solidity/contracts/crowdsale/validation/TimedCrowdsale.sol

/**
 * @title TimedCrowdsale
 * @dev Crowdsale accepting contributions only within a time frame.
 */
contract TimedCrowdsale is Crowdsale {
  using SafeMath for uint256;

  uint256 private _openingTime;
  uint256 private _closingTime;

  /**
   * @dev Reverts if not in crowdsale time range.
   */
  modifier onlyWhileOpen {
    require(isOpen());
    _;
  }

  /**
   * @dev Constructor, takes crowdsale opening and closing times.
   * @param openingTime Crowdsale opening time
   * @param closingTime Crowdsale closing time
   */
  constructor(uint256 openingTime, uint256 closingTime) internal {
    // solium-disable-next-line security/no-block-members
    require(openingTime >= block.timestamp);
    require(closingTime > openingTime);

    _openingTime = openingTime;
    _closingTime = closingTime;
  }

  /**
   * @return the crowdsale opening time.
   */
  function openingTime() public view returns(uint256) {
    return _openingTime;
  }

  /**
   * @return the crowdsale closing time.
   */
  function closingTime() public view returns(uint256) {
    return _closingTime;
  }

  /**
   * @return true if the crowdsale is open, false otherwise.
   */
  function isOpen() public view returns (bool) {
    // solium-disable-next-line security/no-block-members
    return block.timestamp >= _openingTime && block.timestamp <= _closingTime;
  }

  /**
   * @dev Checks whether the period in which the crowdsale is open has already elapsed.
   * @return Whether crowdsale period has elapsed
   */
  function hasClosed() public view returns (bool) {
    // solium-disable-next-line security/no-block-members
    return block.timestamp > _closingTime;
  }

  /**
   * @dev Extend parent behavior requiring to be within contributing period
   * @param beneficiary Token purchaser
   * @param weiAmount Amount of wei contributed
   */
  function _preValidatePurchase(
    address beneficiary,
    uint256 weiAmount
  )
    internal
    onlyWhileOpen
    view
  {
    super._preValidatePurchase(beneficiary, weiAmount);
  }

}

// File: openzeppelin-solidity/contracts/crowdsale/distribution/FinalizableCrowdsale.sol

/**
 * @title FinalizableCrowdsale
 * @dev Extension of Crowdsale with a one-off finalization action, where one
 * can do extra work after finishing.
 */
contract FinalizableCrowdsale is TimedCrowdsale {
  using SafeMath for uint256;

  bool private _finalized;

  event CrowdsaleFinalized();

  constructor() internal {
    _finalized = false;
  }

  /**
   * @return true if the crowdsale is finalized, false otherwise.
   */
  function finalized() public view returns (bool) {
    return _finalized;
  }

  /**
   * @dev Must be called after crowdsale ends, to do some extra finalization
   * work. Calls the contract's finalization function.
   */
  function finalize() public {
    require(!_finalized);
    require(hasClosed());

    _finalized = true;

    _finalization();
    emit CrowdsaleFinalized();
  }

  /**
   * @dev Can be overridden to add finalization logic. The overriding function
   * should call super._finalization() to ensure the chain of finalization is
   * executed entirely.
   */
  function _finalization() internal {
  }
}

// File: openzeppelin-solidity/contracts/ownership/Secondary.sol

/**
 * @title Secondary
 * @dev A Secondary contract can only be used by its primary account (the one that created it)
 */
contract Secondary {
  address private _primary;

  event PrimaryTransferred(
    address recipient
  );

  /**
   * @dev Sets the primary account to the one that is creating the Secondary contract.
   */
  constructor() internal {
    _primary = msg.sender;
    emit PrimaryTransferred(_primary);
  }

  /**
   * @dev Reverts if called from any account other than the primary.
   */
  modifier onlyPrimary() {
    require(msg.sender == _primary);
    _;
  }

  /**
   * @return the address of the primary.
   */
  function primary() public view returns (address) {
    return _primary;
  }
  
  /**
   * @dev Transfers contract to a new primary.
   * @param recipient The address of new primary. 
   */
  function transferPrimary(address recipient) public onlyPrimary {
    require(recipient != address(0));
    _primary = recipient;
    emit PrimaryTransferred(_primary);
  }
}

// File: openzeppelin-solidity/contracts/payment/escrow/Escrow.sol

/**
 * @title Escrow
 * @dev Base escrow contract, holds funds designated for a payee until they
 * withdraw them.
 * @dev Intended usage: This contract (and derived escrow contracts) should be a
 * standalone contract, that only interacts with the contract that instantiated
 * it. That way, it is guaranteed that all Ether will be handled according to
 * the Escrow rules, and there is no need to check for payable functions or
 * transfers in the inheritance tree. The contract that uses the escrow as its
 * payment method should be its primary, and provide public methods redirecting
 * to the escrow's deposit and withdraw.
 */
contract Escrow is Secondary {
  using SafeMath for uint256;

  event Deposited(address indexed payee, uint256 weiAmount);
  event Withdrawn(address indexed payee, uint256 weiAmount);

  mapping(address => uint256) private _deposits;

  function depositsOf(address payee) public view returns (uint256) {
    return _deposits[payee];
  }

  /**
  * @dev Stores the sent amount as credit to be withdrawn.
  * @param payee The destination address of the funds.
  */
  function deposit(address payee) public onlyPrimary payable {
    uint256 amount = msg.value;
    _deposits[payee] = _deposits[payee].add(amount);

    emit Deposited(payee, amount);
  }

  /**
  * @dev Withdraw accumulated balance for a payee.
  * @param payee The address whose funds will be withdrawn and transferred to.
  */
  function withdraw(address payee) public onlyPrimary {
    uint256 payment = _deposits[payee];

    _deposits[payee] = 0;

    payee.transfer(payment);

    emit Withdrawn(payee, payment);
  }
}

// File: openzeppelin-solidity/contracts/payment/escrow/ConditionalEscrow.sol

/**
 * @title ConditionalEscrow
 * @dev Base abstract escrow to only allow withdrawal if a condition is met.
 * @dev Intended usage: See Escrow.sol. Same usage guidelines apply here.
 */
contract ConditionalEscrow is Escrow {
  /**
  * @dev Returns whether an address is allowed to withdraw their funds. To be
  * implemented by derived contracts.
  * @param payee The destination address of the funds.
  */
  function withdrawalAllowed(address payee) public view returns (bool);

  function withdraw(address payee) public {
    require(withdrawalAllowed(payee));
    super.withdraw(payee);
  }
}

// File: openzeppelin-solidity/contracts/payment/escrow/RefundEscrow.sol

/**
 * @title RefundEscrow
 * @dev Escrow that holds funds for a beneficiary, deposited from multiple
 * parties.
 * @dev Intended usage: See Escrow.sol. Same usage guidelines apply here.
 * @dev The primary account (that is, the contract that instantiates this
 * contract) may deposit, close the deposit period, and allow for either
 * withdrawal by the beneficiary, or refunds to the depositors. All interactions
 * with RefundEscrow will be made through the primary contract. See the
 * RefundableCrowdsale contract for an example of RefundEscrow’s use.
 */
contract RefundEscrow is ConditionalEscrow {
  enum State { Active, Refunding, Closed }

  event RefundsClosed();
  event RefundsEnabled();

  State private _state;
  address private _beneficiary;

  /**
   * @dev Constructor.
   * @param beneficiary The beneficiary of the deposits.
   */
  constructor(address beneficiary) public {
    require(beneficiary != address(0));
    _beneficiary = beneficiary;
    _state = State.Active;
  }

  /**
   * @return the current state of the escrow.
   */
  function state() public view returns (State) {
    return _state;
  }

  /**
   * @return the beneficiary of the escrow.
   */
  function beneficiary() public view returns (address) {
    return _beneficiary;
  }

  /**
   * @dev Stores funds that may later be refunded.
   * @param refundee The address funds will be sent to if a refund occurs.
   */
  function deposit(address refundee) public payable {
    require(_state == State.Active);
    super.deposit(refundee);
  }

  /**
   * @dev Allows for the beneficiary to withdraw their funds, rejecting
   * further deposits.
   */
  function close() public onlyPrimary {
    require(_state == State.Active);
    _state = State.Closed;
    emit RefundsClosed();
  }

  /**
   * @dev Allows for refunds to take place, rejecting further deposits.
   */
  function enableRefunds() public onlyPrimary {
    require(_state == State.Active);
    _state = State.Refunding;
    emit RefundsEnabled();
  }

  /**
   * @dev Withdraws the beneficiary's funds.
   */
  function beneficiaryWithdraw() public {
    require(_state == State.Closed);
    _beneficiary.transfer(address(this).balance);
  }

  /**
   * @dev Returns whether refundees can withdraw their deposits (be refunded).
   */
  function withdrawalAllowed(address payee) public view returns (bool) {
    return _state == State.Refunding;
  }
}

// File: openzeppelin-solidity/contracts/crowdsale/distribution/RefundableCrowdsale.sol

/**
 * @title RefundableCrowdsale
 * @dev Extension of Crowdsale contract that adds a funding goal, and
 * the possibility of users getting a refund if goal is not met.
 * WARNING: note that if you allow tokens to be traded before the goal 
 * is met, then an attack is possible in which the attacker purchases 
 * tokens from the crowdsale and when they sees that the goal is 
 * unlikely to be met, they sell their tokens (possibly at a discount).
 * The attacker will be refunded when the crowdsale is finalized, and
 * the users that purchased from them will be left with worthless 
 * tokens. There are many possible ways to avoid this, like making the
 * the crowdsale inherit from PostDeliveryCrowdsale, or imposing 
 * restrictions on token trading until the crowdsale is finalized.
 * This is being discussed in 
 * https://github.com/OpenZeppelin/openzeppelin-solidity/issues/877
 * This contract will be updated when we agree on a general solution
 * for this problem.
 */
contract RefundableCrowdsale is FinalizableCrowdsale {
  using SafeMath for uint256;

  // minimum amount of funds to be raised in weis
  uint256 private _goal;

  // refund escrow used to hold funds while crowdsale is running
  RefundEscrow private _escrow;

  /**
   * @dev Constructor, creates RefundEscrow.
   * @param goal Funding goal
   */
  constructor(uint256 goal) internal {
    require(goal > 0);
    _escrow = new RefundEscrow(wallet());
    _goal = goal;
  }

  /**
   * @return minimum amount of funds to be raised in wei.
   */
  function goal() public view returns(uint256) {
    return _goal;
  }

  /**
   * @dev Investors can claim refunds here if crowdsale is unsuccessful
   * @param beneficiary Whose refund will be claimed.
   */
  function claimRefund(address beneficiary) public {
    require(finalized());
    require(!goalReached());

    _escrow.withdraw(beneficiary);
  }

  /**
   * @dev Checks whether funding goal was reached.
   * @return Whether funding goal was reached
   */
  function goalReached() public view returns (bool) {
    return weiRaised() >= _goal;
  }

  /**
   * @dev escrow finalization task, called when finalize() is called
   */
  function _finalization() internal {
    if (goalReached()) {
      _escrow.close();
      _escrow.beneficiaryWithdraw();
    } else {
      _escrow.enableRefunds();
    }

    super._finalization();
  }

  /**
   * @dev Overrides Crowdsale fund forwarding, sending funds to escrow.
   */
  function _forwardFunds() internal {
    _escrow.deposit.value(msg.value)(msg.sender);
  }

}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20.sol

/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
 * Originally based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract ERC20 is IERC20 {
  using SafeMath for uint256;

  mapping (address => uint256) private _balances;

  mapping (address => mapping (address => uint256)) private _allowed;

  uint256 private _totalSupply;

  /**
  * @dev Total number of tokens in existence
  */
  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param owner The address to query the balance of.
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address owner) public view returns (uint256) {
    return _balances[owner];
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param owner address The address which owns the funds.
   * @param spender address The address which will spend the funds.
   * @return A uint256 specifying the amount of tokens still available for the spender.
   */
  function allowance(
    address owner,
    address spender
   )
    public
    view
    returns (uint256)
  {
    return _allowed[owner][spender];
  }

  /**
  * @dev Transfer token for a specified address
  * @param to The address to transfer to.
  * @param value The amount to be transferred.
  */
  function transfer(address to, uint256 value) public returns (bool) {
    _transfer(msg.sender, to, value);
    return true;
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   * Beware that changing an allowance with this method brings the risk that someone may use both the old
   * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
   * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
   * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
   * @param spender The address which will spend the funds.
   * @param value The amount of tokens to be spent.
   */
  function approve(address spender, uint256 value) public returns (bool) {
    require(spender != address(0));

    _allowed[msg.sender][spender] = value;
    emit Approval(msg.sender, spender, value);
    return true;
  }

  /**
   * @dev Transfer tokens from one address to another
   * @param from address The address which you want to send tokens from
   * @param to address The address which you want to transfer to
   * @param value uint256 the amount of tokens to be transferred
   */
  function transferFrom(
    address from,
    address to,
    uint256 value
  )
    public
    returns (bool)
  {
    require(value <= _allowed[from][msg.sender]);

    _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
    _transfer(from, to, value);
    return true;
  }

  /**
   * @dev Increase the amount of tokens that an owner allowed to a spender.
   * approve should be called when allowed_[_spender] == 0. To increment
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param spender The address which will spend the funds.
   * @param addedValue The amount of tokens to increase the allowance by.
   */
  function increaseAllowance(
    address spender,
    uint256 addedValue
  )
    public
    returns (bool)
  {
    require(spender != address(0));

    _allowed[msg.sender][spender] = (
      _allowed[msg.sender][spender].add(addedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  /**
   * @dev Decrease the amount of tokens that an owner allowed to a spender.
   * approve should be called when allowed_[_spender] == 0. To decrement
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param spender The address which will spend the funds.
   * @param subtractedValue The amount of tokens to decrease the allowance by.
   */
  function decreaseAllowance(
    address spender,
    uint256 subtractedValue
  )
    public
    returns (bool)
  {
    require(spender != address(0));

    _allowed[msg.sender][spender] = (
      _allowed[msg.sender][spender].sub(subtractedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  /**
  * @dev Transfer token for a specified addresses
  * @param from The address to transfer from.
  * @param to The address to transfer to.
  * @param value The amount to be transferred.
  */
  function _transfer(address from, address to, uint256 value) internal {
    require(value <= _balances[from]);
    require(to != address(0));

    _balances[from] = _balances[from].sub(value);
    _balances[to] = _balances[to].add(value);
    emit Transfer(from, to, value);
  }

  /**
   * @dev Internal function that mints an amount of the token and assigns it to
   * an account. This encapsulates the modification of balances such that the
   * proper events are emitted.
   * @param account The account that will receive the created tokens.
   * @param value The amount that will be created.
   */
  function _mint(address account, uint256 value) internal {
    require(account != 0);
    _totalSupply = _totalSupply.add(value);
    _balances[account] = _balances[account].add(value);
    emit Transfer(address(0), account, value);
  }

  /**
   * @dev Internal function that burns an amount of the token of a given
   * account.
   * @param account The account whose tokens will be burnt.
   * @param value The amount that will be burnt.
   */
  function _burn(address account, uint256 value) internal {
    require(account != 0);
    require(value <= _balances[account]);

    _totalSupply = _totalSupply.sub(value);
    _balances[account] = _balances[account].sub(value);
    emit Transfer(account, address(0), value);
  }

  /**
   * @dev Internal function that burns an amount of the token of a given
   * account, deducting from the sender's allowance for said account. Uses the
   * internal burn function.
   * @param account The account whose tokens will be burnt.
   * @param value The amount that will be burnt.
   */
  function _burnFrom(address account, uint256 value) internal {
    require(value <= _allowed[account][msg.sender]);

    // Should https://github.com/OpenZeppelin/zeppelin-solidity/issues/707 be accepted,
    // this function needs to emit an event with the updated approval.
    _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(
      value);
    _burn(account, value);
  }
}

// File: openzeppelin-solidity/contracts/access/Roles.sol

/**
 * @title Roles
 * @dev Library for managing addresses assigned to a Role.
 */
library Roles {
  struct Role {
    mapping (address => bool) bearer;
  }

  /**
   * @dev give an account access to this role
   */
  function add(Role storage role, address account) internal {
    require(account != address(0));
    require(!has(role, account));

    role.bearer[account] = true;
  }

  /**
   * @dev remove an account's access to this role
   */
  function remove(Role storage role, address account) internal {
    require(account != address(0));
    require(has(role, account));

    role.bearer[account] = false;
  }

  /**
   * @dev check if an account has this role
   * @return bool
   */
  function has(Role storage role, address account)
    internal
    view
    returns (bool)
  {
    require(account != address(0));
    return role.bearer[account];
  }
}

// File: openzeppelin-solidity/contracts/access/roles/MinterRole.sol

contract MinterRole {
  using Roles for Roles.Role;

  event MinterAdded(address indexed account);
  event MinterRemoved(address indexed account);

  Roles.Role private minters;

  constructor() internal {
    _addMinter(msg.sender);
  }

  modifier onlyMinter() {
    require(isMinter(msg.sender));
    _;
  }

  function isMinter(address account) public view returns (bool) {
    return minters.has(account);
  }

  function addMinter(address account) public onlyMinter {
    _addMinter(account);
  }

  function renounceMinter() public {
    _removeMinter(msg.sender);
  }

  function _addMinter(address account) internal {
    minters.add(account);
    emit MinterAdded(account);
  }

  function _removeMinter(address account) internal {
    minters.remove(account);
    emit MinterRemoved(account);
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20Mintable.sol

/**
 * @title ERC20Mintable
 * @dev ERC20 minting logic
 */
contract ERC20Mintable is ERC20, MinterRole {
  /**
   * @dev Function to mint tokens
   * @param to The address that will receive the minted tokens.
   * @param value The amount of tokens to mint.
   * @return A boolean that indicates if the operation was successful.
   */
  function mint(
    address to,
    uint256 value
  )
    public
    onlyMinter
    returns (bool)
  {
    _mint(to, value);
    return true;
  }
}

// File: openzeppelin-solidity/contracts/crowdsale/emission/MintedCrowdsale.sol

/**
 * @title MintedCrowdsale
 * @dev Extension of Crowdsale contract whose tokens are minted in each purchase.
 * Token ownership should be transferred to MintedCrowdsale for minting.
 */
contract MintedCrowdsale is Crowdsale {
  constructor() internal {}

  /**
   * @dev Overrides delivery by minting tokens upon purchase.
   * @param beneficiary Token purchaser
   * @param tokenAmount Number of tokens to be minted
   */
  function _deliverTokens(
    address beneficiary,
    uint256 tokenAmount
  )
    internal
  {
    // Potentially dangerous assumption about the type of the token.
    require(
      ERC20Mintable(address(token())).mint(beneficiary, tokenAmount));
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20Capped.sol

/**
 * @title Capped token
 * @dev Mintable token with a token cap.
 */
contract ERC20Capped is ERC20Mintable {

  uint256 private _cap;

  constructor(uint256 cap)
    public
  {
    require(cap > 0);
    _cap = cap;
  }

  /**
   * @return the cap for the token minting.
   */
  function cap() public view returns(uint256) {
    return _cap;
  }

  function _mint(address account, uint256 value) internal {
    require(totalSupply().add(value) <= _cap);
    super._mint(account, value);
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20Burnable.sol

/**
 * @title Burnable Token
 * @dev Token that can be irreversibly burned (destroyed).
 */
contract ERC20Burnable is ERC20 {

  /**
   * @dev Burns a specific amount of tokens.
   * @param value The amount of token to be burned.
   */
  function burn(uint256 value) public {
    _burn(msg.sender, value);
  }

  /**
   * @dev Burns a specific amount of tokens from the target address and decrements allowance
   * @param from address The address which you want to send tokens from
   * @param value uint256 The amount of token to be burned
   */
  function burnFrom(address from, uint256 value) public {
    _burnFrom(from, value);
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol

/**
 * @title ERC20Detailed token
 * @dev The decimals are only for visualization purposes.
 * All the operations are done using the smallest and indivisible token unit,
 * just as on Ethereum all the operations are done in wei.
 */
contract ERC20Detailed is IERC20 {
  string private _name;
  string private _symbol;
  uint8 private _decimals;

  constructor(string name, string symbol, uint8 decimals) public {
    _name = name;
    _symbol = symbol;
    _decimals = decimals;
  }

  /**
   * @return the name of the token.
   */
  function name() public view returns(string) {
    return _name;
  }

  /**
   * @return the symbol of the token.
   */
  function symbol() public view returns(string) {
    return _symbol;
  }

  /**
   * @return the number of decimals of the token.
   */
  function decimals() public view returns(uint8) {
    return _decimals;
  }
}

// File: openzeppelin-solidity/contracts/access/roles/PauserRole.sol

contract PauserRole {
  using Roles for Roles.Role;

  event PauserAdded(address indexed account);
  event PauserRemoved(address indexed account);

  Roles.Role private pausers;

  constructor() internal {
    _addPauser(msg.sender);
  }

  modifier onlyPauser() {
    require(isPauser(msg.sender));
    _;
  }

  function isPauser(address account) public view returns (bool) {
    return pausers.has(account);
  }

  function addPauser(address account) public onlyPauser {
    _addPauser(account);
  }

  function renouncePauser() public {
    _removePauser(msg.sender);
  }

  function _addPauser(address account) internal {
    pausers.add(account);
    emit PauserAdded(account);
  }

  function _removePauser(address account) internal {
    pausers.remove(account);
    emit PauserRemoved(account);
  }
}

// File: openzeppelin-solidity/contracts/lifecycle/Pausable.sol

/**
 * @title Pausable
 * @dev Base contract which allows children to implement an emergency stop mechanism.
 */
contract Pausable is PauserRole {
  event Paused(address account);
  event Unpaused(address account);

  bool private _paused;

  constructor() internal {
    _paused = false;
  }

  /**
   * @return true if the contract is paused, false otherwise.
   */
  function paused() public view returns(bool) {
    return _paused;
  }

  /**
   * @dev Modifier to make a function callable only when the contract is not paused.
   */
  modifier whenNotPaused() {
    require(!_paused);
    _;
  }

  /**
   * @dev Modifier to make a function callable only when the contract is paused.
   */
  modifier whenPaused() {
    require(_paused);
    _;
  }

  /**
   * @dev called by the owner to pause, triggers stopped state
   */
  function pause() public onlyPauser whenNotPaused {
    _paused = true;
    emit Paused(msg.sender);
  }

  /**
   * @dev called by the owner to unpause, returns to normal state
   */
  function unpause() public onlyPauser whenPaused {
    _paused = false;
    emit Unpaused(msg.sender);
  }
}

// File: contracts\SsenToken.sol

contract SsenToken is ERC20Mintable, ERC20Detailed,  Pausable {

    // define initial coin supply here
    uint256 public constant INITIAL_SUPPLY = 10000000000 * (10 ** uint256(decimals()));

    /**
     * @dev Constructor that gives msg.sender all of existing tokens.
     */
    constructor () public ERC20Detailed("SSEN Token", "SSEN", 18)    {
		
		
        _mint(msg.sender, INITIAL_SUPPLY);
    }
	
	
	/**
     * @dev Burns a specific amount of tokens.
     * @param value The amount of token to be burned.
     */
    function burn(uint256 value) public {
        _burn(msg.sender, value);
    }

    /**
     * @dev Burns a specific amount of tokens from the target address and decrements allowance
     * @param from address The address which you want to send tokens from
     * @param value uint256 The amount of token to be burned
     */
    function burnFrom(address from, uint256 value) public {
        _burnFrom(from, value);
    }
	

	
	function transfer(address to, uint256 value) public whenNotPaused returns (bool) {
        return super.transfer(to, value);
    }

    function transferFrom(address from,address to, uint256 value) public whenNotPaused returns (bool) {
        return super.transferFrom(from, to, value);
    }

    function approve(address spender, uint256 value) public whenNotPaused returns (bool) {
        return super.approve(spender, value);
    }

    function increaseAllowance(address spender, uint addedValue) public whenNotPaused returns (bool success) {
        return super.increaseAllowance(spender, addedValue);
    }

    function decreaseAllowance(address spender, uint subtractedValue) public whenNotPaused returns (bool success) {
        return super.decreaseAllowance(spender, subtractedValue);
    }
	
}