contract TokenERC20 is Ownable
{
    using SafeMath for uint;

    // Public variables of the token
    string public name;
    string public symbol;
    uint256 public decimals = 18;
    uint256 DEC = 10 ** uint256(decimals);
    uint256 public totalSupply;
    uint256 public avaliableSupply;
    uint256 public buyPrice = 1000000000000000000 wei;

    // This creates an array with all balances
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    // This generates a public event on the blockchain that will notify clients
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Burn(address indexed from, uint256 value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);

    /**
     * Constrctor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    function TokenERC20(
        uint256 initialSupply,
        string tokenName,
        string tokenSymbol
    ) public
    {
        totalSupply = initialSupply.mul(DEC);  // Update total supply with the decimal amount
        balanceOf[this] = totalSupply;         // Give the creator all initial tokens
        avaliableSupply = balanceOf[this];     // Show how much tokens on contract
        name = tokenName;                      // Set the name for display purposes
        symbol = tokenSymbol;                  // Set the symbol for display purposes
    }

    /**
     * Internal transfer, only can be called by this contract
     *
     * @param _from - address of the contract
     * @param _to - address of the investor
     * @param _value - tokens for the investor
     */
    function _transfer(address _from, address _to, uint256 _value) internal
    {
        // Prevent transfer to 0x0 address. Use burn() instead
        require(_to != 0x0);
        // Check if the sender has enough
        require(balanceOf[_from] >= _value);
        // Check for overflows
        require(balanceOf[_to].add(_value) > balanceOf[_to]);
        // Save this for an assertion in the future
        uint previousBalances = balanceOf[_from].add(balanceOf[_to]);
        // Subtract from the sender
        balanceOf[_from] = balanceOf[_from].sub(_value);
        // Add the same to the recipient
        balanceOf[_to] = balanceOf[_to].add(_value);

        Transfer(_from, _to, _value);
        // Asserts are used to use static analysis to find bugs in your code. They should never fail
        assert(balanceOf[_from].add(balanceOf[_to]) == previousBalances);
    }

    /**
     * Transfer tokens
     *
     * Send `_value` tokens to `_to` from your account
     *
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transfer(address _to, uint256 _value) public
    {
        _transfer(msg.sender, _to, _value);
    }

    /**
     * Transfer tokens from other address
     *
     * Send `_value` tokens to `_to` in behalf of `_from`
     *
     * @param _from The address of the sender
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transferFrom(address _from, address _to, uint256 _value) public
        returns (bool success)
    {
        require(_value <= allowance[_from][msg.sender]);     // Check allowance

        allowance[_from][msg.sender] = allowance[_from][msg.sender].sub(_value);
        _transfer(_from, _to, _value);

        return true;
    }

    /**
     * Set allowance for other address
     *
     * Allows `_spender` to spend no more than `_value` tokens in your behalf
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     */
    function approve(address _spender, uint256 _value) public
        returns (bool success)
    {
        allowance[msg.sender][_spender] = _value;

        return true;
    }

    /**
     * Set allowance for other address and notify
     *
     * Allows `_spender` to spend no more than `_value` tokens in your behalf, and then ping the contract about it
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     * @param _extraData some extra information to send to the approved contract
     */
    function approveAndCall(address _spender, uint256 _value, bytes _extraData) public onlyOwner
        returns (bool success)
    {
        tokenRecipient spender = tokenRecipient(_spender);

        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);

            return true;
        }
    }

    /**
     * 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
     */
    function increaseApproval (address _spender, uint _addedValue) public
        returns (bool success)
    {
        allowance[msg.sender][_spender] = allowance[msg.sender][_spender].add(_addedValue);

        Approval(msg.sender, _spender, allowance[msg.sender][_spender]);

        return true;
    }

    function decreaseApproval (address _spender, uint _subtractedValue) public
        returns (bool success)
    {
        uint oldValue = allowance[msg.sender][_spender];

        if (_subtractedValue > oldValue) {
            allowance[msg.sender][_spender] = 0;
        } else {
            allowance[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }

        Approval(msg.sender, _spender, allowance[msg.sender][_spender]);

        return true;
    }

    /**
     * Destroy tokens
     *
     * Remove `_value` tokens from the system irreversibly
     *
     * @param _value the amount of money to burn
     */
    function burn(uint256 _value) public onlyOwner
        returns (bool success)
    {
        require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough

        balanceOf[msg.sender] = balanceOf[msg.sender].sub(_value);  // Subtract from the sender
        totalSupply = totalSupply.sub(_value);                      // Updates totalSupply
        avaliableSupply = avaliableSupply.sub(_value);

        Burn(msg.sender, _value);

        return true;
    }

    /**
     * Destroy tokens from other account
     *
     * Remove `_value` tokens from the system irreversibly on behalf of `_from`.
     *
     * @param _from the address of the sender
     * @param _value the amount of money to burn
     */
    function burnFrom(address _from, uint256 _value) public onlyOwner
        returns (bool success)
    {
        require(balanceOf[_from] >= _value);                // Check if the targeted balance is enough
        require(_value <= allowance[_from][msg.sender]);    // Check allowance

        balanceOf[_from] = balanceOf[_from].sub(_value);    // Subtract from the targeted balance
        allowance[_from][msg.sender] = allowance[_from][msg.sender].sub(_value);    // Subtract from the sender's allowance
        totalSupply = totalSupply.sub(_value);              // Update totalSupply
        avaliableSupply = avaliableSupply.sub(_value);

        Burn(_from, _value);

        return true;
    }
}
function increaseApproval (address _spender, uint _addedValue) public
        returns (bool success)
    {
        allowance[msg.sender][_spender] = allowance[msg.sender][_spender].add(_addedValue);

        Approval(msg.sender, _spender, allowance[msg.sender][_spender]);

        return true;
    }
/**
 * 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
 */