/**
 *Submitted for verification at Etherscan.io on 2018-03-22
*/

pragma solidity ^0.4.18;

interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; }

contract JJKcoin {
   // Public variables of the token
   string public name = "JJKcoin";
   string public symbol = "JKK";
   uint8 public decimals = 0;
   // 18 decimals is the strongly suggested default, avoid changing it
   uint256 public totalSupply = 1800000000;

   // 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);

   // This notifies clients about the amount burnt
   event Burn(address indexed from, uint256 value);

   /**
    * Constructor function
    *
    * Initializes contract with initial supply tokens to the creator of the contract
    */
   function JJKcoin(
       uint256 initialSupply,
       string tokenName,
       string tokenSymbol
   ) public {
       totalSupply = initialSupply * 18 ** uint256(decimals);  // Update total supply with the decimal amount
       balanceOf[msg.sender] = totalSupply;                // Give the creator all initial tokens
       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
    */
   function _transfer(address _from, address _to, uint _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] + _value > balanceOf[_to]);
       // Save this for an assertion in the future
       uint previousBalances = balanceOf[_from] + balanceOf[_to];
       // Subtract from the sender
       balanceOf[_from] -= _value;
       // Add the same to the recipient
       balanceOf[_to] += _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] + 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` on 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] -= _value;
       _transfer(_from, _to, _value);
       return true;
   }

   /**
    * Set allowance for other address
    *
    * Allows `_spender` to spend no more than `_value` tokens on 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 on 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
       returns (bool success) {
       tokenRecipient spender = tokenRecipient(_spender);
       if (approve(_spender, _value)) {
           spender.receiveApproval(msg.sender, _value, this, _extraData);
           return true;
       }
   }

   /**
    * Destroy tokens
    *
    * Remove `_value` tokens from the system irreversibly
    *
    * @param _value the amount of money to burn
    */
   function burn(uint256 _value) public returns (bool success) {
       require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough
       balanceOf[msg.sender] -= _value;            // Subtract from the sender
       totalSupply -= _value;                      // Updates totalSupply
       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 returns (bool success) {
       require(balanceOf[_from] >= _value);                // Check if the targeted balance is enough
       require(_value <= allowance[_from][msg.sender]);    // Check allowance
       balanceOf[_from] -= _value;                         // Subtract from the targeted balance
       allowance[_from][msg.sender] -= _value;             // Subtract from the sender's allowance
       totalSupply -= _value;                              // Update totalSupply
       Burn(_from, _value);
       return true;
   }
}