pragma solidity ^0.4.4;
contract MRNContract {
/// @return total amount of tokens
 function totalSupply() constant returns (uint256 supply) {}
/// @param _owner The address from which the balance will be retrieved
 /// @return The balance
 function balanceOf(address _owner) constant returns (uint256 balance) {}
/// @notice send `_value` token to `_to` from `msg.sender`
 /// @param _to The address of the recipient
 /// @param _value The amount of token to be transferred
 /// @return Whether the transfer was successful or not
 function transfer(address _to, uint256 _value) returns (bool success) {}
/// @notice send `_value` token to `_to` from `_from` on the condition it is approved by `_from`
 /// @param _from The address of the sender
 /// @param _to The address of the recipient
 /// @param _value The amount of token to be transferred
 /// @return Whether the transfer was successful or not
 function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {}
/// @notice `msg.sender` approves `_addr` to spend `_value` tokens
 /// @param _spender The address of the account able to transfer the tokens
 /// @param _value The amount of wei to be approved for transfer
 /// @return Whether the approval was successful or not
 function approve(address _spender, uint256 _value) returns (bool success) {}
/// @param _owner The address of the account owning tokens
 /// @param _spender The address of the account able to transfer the tokens
 /// @return Amount of remaining tokens allowed to spent
 function allowance(address _owner, address _spender) constant returns (uint256 remaining) {}
event Transfer(address indexed _from, address indexed _to, uint256 _value);
 event Approval(address indexed _owner, address indexed _spender, uint256 _value);
 
}
contract StandardToken is MRNContract {
function transfer(address _to, uint256 _value) returns (bool success) {
 //Default assumes totalSupply can’t be over max (2²⁵⁶ — 1).
 //If your token leaves out totalSupply and can issue more tokens as time goes on, you need to check if it doesn’t wrap.
 //Replace the if with this one instead.
 //if (balances[msg.sender] >= _value && balances[_to] + _value > balances[_to]) {
 if (balances[msg.sender] >= _value && _value > 0) {
 balances[msg.sender] -= _value;
 balances[_to] += _value;
 Transfer(msg.sender, _to, _value);
 return true;
 } else { return false; }
 }
function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
 //same as above. Replace this line with the following if you want to protect against wrapping uints.
 //if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && balances[_to] + _value > balances[_to]) {
 if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0) {
 balances[_to] += _value;
 balances[_from] -= _value;
 allowed[_from][msg.sender] -= _value;
 Transfer(_from, _to, _value);
 return true;
 } else { return false; }
 }
function balanceOf(address _owner) constant returns (uint256 balance) {
 return balances[_owner];
 }
function approve(address _spender, uint256 _value) returns (bool success) {
 allowed[msg.sender][_spender] = _value;
 Approval(msg.sender, _spender, _value);
 return true;
 }
function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
 return allowed[_owner][_spender];
 }
mapping (address => uint256) balances;
 mapping (address => mapping (address => uint256)) allowed;
 uint256 public totalSupply;
}
//name this contract whatever you’d like
contract Token is StandardToken {
function () {
 //if ether is sent to this address, send it back.
 throw;
 }
/* Public variables of the token */
/*
 NOTE:
 The following variables are OPTIONAL vanities. One does not have to include them.
 They allow one to customise the token contract & in no way influences the core functionality.
 Some wallets/interfaces might not even bother to look at this information.
 */
 string public name; //fancy name: eg Simon Bucks
 uint8 public decimals; //How many decimals to show. ie. There could 1000 base units with 3 decimals. Meaning 0.980 SBX = 980 base units. It’s like comparing 1 wei to 1 ether.
 string public symbol; //An identifier: eg SBX
 string public version = 'H1.0'; //human 0.1 standard. Just an arbitrary versioning scheme.
//
//make sure this function name matches the contract name above. So if you’re token is called TutorialToken, make sure the //contract name above is also TutorialToken instead of ERC20Token
function Token(
 ) {
 balances[msg.sender] = 100000000000000;
 totalSupply = 100000000000000;
 name = 'MRN';
 decimals = 6;
 symbol = 'MRN';
 }
/* Approves and then calls the receiving contract */
 function approveAndCall(address _spender, uint256 _value, bytes _extraData) returns (bool success) {
 allowed[msg.sender][_spender] = _value;
 Approval(msg.sender, _spender, _value);
//call the receiveApproval function on the contract you want to be notified. This crafts the function signature manually so one doesn’t have to include a contract in here just for this.
 //receiveApproval(address _from, uint256 _value, address _tokenContract, bytes _extraData)
 //it is assumed that when does this that the call *should* succeed, otherwise one would use vanilla approve instead.
 if(!_spender.call(bytes4(bytes32(sha3('receiveApproval(address,uint256,address,bytes)'))), msg.sender, _value, this, _extraData)) { throw; }
 return true;
 }
}