pragma solidity ^0.4.23;

library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
   
    if (a == 0) {
      return 0;
    }
    c = a * b;
    assert(c / a == b);
    return c;
  }
  function div(uint256 a, uint256 b) internal pure returns (uint256) {   
    return a / b;
  }  
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }
  function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
    c = a + b;
    assert(c >= a);
    return c;
  }
}

contract ERC20Basic {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}

contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender)
    public view returns (uint256);
  function transferFrom(address from, address to, uint256 value)
    public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}

contract Ownable {
  address public owner;
  event OwnershipRenounced(address indexed previousOwner);
  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );
  constructor() public {
    owner = msg.sender;
  }
  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }
  function renounceOwnership() public onlyOwner {
    emit OwnershipRenounced(owner);
    owner = address(0);
  }
  function transferOwnership(address _newOwner) public onlyOwner {
    _transferOwnership(_newOwner);
  }
  function _transferOwnership(address _newOwner) internal {
    require(_newOwner != address(0));
    emit OwnershipTransferred(owner, _newOwner);
    owner = _newOwner;
  }
}

contract BasicToken is ERC20Basic {
  using SafeMath for uint256;
  mapping(address => uint256) balances;
  uint256 totalSupply_;
  function totalSupply() public view returns (uint256) {
    return totalSupply_;
  }
  function transfer(address _to, uint256 _value) 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 (uint256) {
    return balances[_owner];
  }
}

contract BurnableToken is BasicToken {
  event Burn(address indexed burner, uint256 value);
  function burn(uint256 _value) public {
    _burn(msg.sender, _value);
  }
  function _burn(address _who, uint256 _value) internal {
    require(_value <= balances[_who]);
    balances[_who] = balances[_who].sub(_value);
    totalSupply_ = totalSupply_.sub(_value);
    emit Burn(_who, _value);
    emit Transfer(_who, address(0), _value);
  }
}

contract StandardToken is ERC20, BasicToken {
  mapping (address => mapping (address => uint256)) internal allowed;
  function transferFrom(
    address _from,
    address _to,
    uint256 _value
  )
    public
    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, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
  }
  function allowance(
    address _owner,
    address _spender
   )
    public
    view
    returns (uint256)
  {
    return allowed[_owner][_spender];
  }
  function increaseApproval(
    address _spender,
    uint _addedValue
  )
    public
    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
    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;
  }
}

contract StandardBurnableToken is BurnableToken, StandardToken {
  function burnFrom(address _from, uint256 _value) public {
    require(_value <= allowed[_from][msg.sender]);   
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    _burn(_from, _value);
  }
}

contract DetailedERC20 is ERC20 {
  string public name;
  string public symbol;
  uint8 public decimals;
  constructor(string _name, string _symbol, uint8 _decimals) public {
    name = _name;
    symbol = _symbol;
    decimals = _decimals;
  }
}

contract Pausable is Ownable {
  event Pause();
  event Unpause();
  bool public paused = false;
  modifier whenNotPaused() {
    require(!paused);
    _;
  }
  modifier whenPaused() {
    require(paused);
    _;
  }
  function pause() onlyOwner whenNotPaused public {
    paused = true;
    emit Pause();
  }
  function unpause() onlyOwner whenPaused public {
    paused = false;
    emit Unpause();
  }
}

contract PausableToken is StandardToken, Pausable {
  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 increaseApproval(
    address _spender,
    uint _addedValue
  )
    public
    whenNotPaused
    returns (bool success)
  {
    return super.increaseApproval(_spender, _addedValue);
  }
  function decreaseApproval(
    address _spender,
    uint _subtractedValue
  )
    public
    whenNotPaused
    returns (bool success)
  {
    return super.decreaseApproval(_spender, _subtractedValue);
  }
}

contract BaseERC20Token is StandardBurnableToken, PausableToken, DetailedERC20 {
  constructor(
    uint256 _initialAmount,
    uint8 _decimalUnits,
    string _tokenName,
    string _tokenSymbol
  ) DetailedERC20(_tokenName, _tokenSymbol, _decimalUnits) public {
    totalSupply_ = _initialAmount;
    balances[msg.sender] = totalSupply_;
  }
  function _burn(address _from, uint256 _value) internal whenNotPaused {
    super._burn(_from, _value);
  }
}

contract Rebitcoin is BaseERC20Token {
  constructor() BaseERC20Token(2100000000000000, 8, "Rebitcoin", "RBTC") public {    
  }
}