contract Token is ERC20Interface {
    
    using SafeMath for uint;
    
    string public constant symbol = "LNC";
    string public constant name = "Linker Coin";
    uint8 public constant decimals = 18;
    uint256 _totalSupply = 500000000000000000000000000;
    
    //AML & KYC
    mapping (address => bool) public frozenAccount;
    event FrozenFunds(address target, bool frozen);
  
    // Linker coin has  5*10^25 units, each unit has 10^18  minimum fractions which are called 
    // Owner of this contract
    address public owner;

    // Balances for each account
    mapping(address => uint256) balances;

    // Owner of account approves the transfer of an amount to another account
    mapping(address => mapping (address => uint256)) allowed;

    // Functions with this modifier can only be executed by the owner
    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }
    
    function IsFreezedAccount(address _addr) public constant returns (bool) {
        return frozenAccount[_addr];
    }

    // Constructor
    function Token() public {
        owner = msg.sender;
        balances[owner] = _totalSupply;
    }

    function totalSupply() public constant returns (uint256 supply) {
        supply = _totalSupply;
    }

    // What is the balance of a particular account?
    function balanceOf(address _owner) public constant returns (uint256 balance) {
        return balances[_owner];
    }

    // Transfer the balance from owner's account to another account
    function transfer(address _to, uint256 _value) public returns (bool success)
    {
        if (_to != 0x0  // Prevent transfer to 0x0 address.
            && IsFreezedAccount(msg.sender) == false
            && balances[msg.sender] >= _value 
            && _value > 0
            && balances[_to] + _value > balances[_to]) {
            balances[msg.sender] = balances[msg.sender].sub(_value);
            balances[_to] = balances[_to].add(_value);
            Transfer(msg.sender, _to, _value);
            return true;
        } else {
            return false;
        }
    }

    // Send _value amount of tokens from address _from to address _to
    // The transferFrom method is used for a withdraw workflow, allowing contracts to send
    // tokens on your behalf, for example to "deposit" to a contract address and/or to charge
    // fees in sub-currencies; the command should fail unless the _from account has
    // deliberately authorized the sender of the message via some mechanism; we propose
    // these standardized APIs for approval:
    function transferFrom(address _from,address _to, uint256 _value) public returns (bool success) {
        if (_to != 0x0  // Prevent transfer to 0x0 address.
            && IsFreezedAccount(_from) == false
            && balances[_from] >= _value
            && allowed[_from][msg.sender] >= _value
            && _value > 0
            && balances[_to] + _value > balances[_to]) {
            balances[_from] = balances[_from].sub(_value);
            allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
            balances[_to] = balances[_to].add(_value);
            Transfer(_from, _to, _value);
            return true;
        } else {
            return false;
        }
    }

     // Allow _spender to withdraw from your account, multiple times, up to the _value amount.
    // If this function is called again it overwrites the current allowance with _value.
    function approve(address _spender, uint256 _value) public returns (bool success) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }
    
    function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }
    
    function FreezeAccount(address target, bool freeze) onlyOwner public {
        frozenAccount[target] = freeze;
        FrozenFunds(target, freeze);
    }
}
function approve(address _spender, uint256 _value) public returns (bool success) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }
// Allow _spender to withdraw from your account, multiple times, up to the _value amount.
// If this function is called again it overwrites the current allowance with _value.