pragma solidity ^0.4.24;

/**
 * @title SafeMath
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, reverts on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }

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

    return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0); 
    uint256 c = a / b;

    return c;
  }

  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    uint256 c = a - b;

    return c;
  }

  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a);

    return c;
  }

  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0);
    return a % b;
  }
}

/**
 * @title Roles
 */
library Roles {
  struct Role {
    mapping (address => bool) bearer;
  }

  function add(Role storage role, address account) internal {
    require(account != address(0));
    role.bearer[account] = true;
  }

  function remove(Role storage role, address account) internal {
    require(account != address(0));
    role.bearer[account] = false;
  }

  function has(Role storage role, address account)
  internal
  view
  returns (bool)
  {
    require(account != address(0));
    return role.bearer[account];
  }
}

/**
 * @title ERC20 interface
 */
interface ERC20 {
  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);

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

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



/**
 * @title TokenBasic ERC20 token
 */
contract TokenBasic is ERC20 {
  using SafeMath for uint256;
  mapping (address => uint256) private _balances;
  mapping (address => mapping (address => uint256)) private _allowed;
  uint256 private _totalSupply;

  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }

  function balanceOf(address owner) public view returns (uint256) {
    return _balances[owner];
  }

  function allowance(
    address owner,
    address spender
  )
  public
  view
  returns (uint256)
  {
    return _allowed[owner][spender];
  }

  function transfer(address to, uint256 value) public returns (bool) {
    _transfer(msg.sender, to, value);
    return true;
  }

  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;
  }

  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;
  }

  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;
  }

  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);
  }

  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);
  }

  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);
  }

  function _burnFrom(address account, uint256 value) internal {
    require(value <= _allowed[account][msg.sender]);

    _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(
      value);
    _burn(account, value);
  }
}

contract MinterRole {
  using Roles for Roles.Role;

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

  Roles.Role private minters;

  constructor() public {
    _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);
  }
}


/**
 * @title Mintable
 */
contract Mintable is TokenBasic, MinterRole {
  function mint(
    address to,
    uint256 value
  )
  public
  onlyMinter
  returns (bool)
  {
    _mint(to, value);
    return true;
  }
}


/**
 * @title Burnable Token
 */
contract Burnable is TokenBasic {

  function burn(uint256 value) public {
    _burn(msg.sender, value);
  }

  function burnFrom(address from, uint256 value) public {
    _burnFrom(from, value);
  }
}



/**
 * @title NTON
 */
contract NTON is Burnable, Mintable {

  string public constant name = "NTON";
  string public constant symbol = "NTON";
  uint8 public constant decimals = 18;
  uint256 public constant INITIAL_SUPPLY = 3500000000 * (10 ** uint256(decimals));

  constructor(address _owner) public {
    _mint(_owner, INITIAL_SUPPLY);
  }

}