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ballot.sol

pragma solidity ^0.4.6;
contract owned {
    address public owner;
    
    function owned() {
        owner = msg.sender;
    }
    
    modifier onlyOwner {
    if (msg.sender != owner) throw;
    _;
    }
    
    function transferOwnership(address newOwner) onlyOwner {
        owner = newOwner;
    }
}

contract tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _externalData);}

contract token {
    
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;
    uint256 public totalSupply;
    string public name;
    uint8 public decimals;
    string public symbol;
    
    event Transfer(address indexed from, address indexed to, uint256 value);
    
    function token(uint256 initialSupply, string tokenName, uint8 decimalUnits, string tokenSymbol) {
        balanceOf[msg.sender] = initialSupply;
        totalSupply = initialSupply;
        decimals = decimalUnits;
        symbol = tokenSymbol;
        name = tokenName;
    }
    
    function transfer(address _to, uint256 _value) {
        if(balanceOf[msg.sender] < _value) throw;
        if(balanceOf[_to] + _value < balanceOf[_to]) throw;
        balanceOf[_to] += _value;
        balanceOf[msg.sender] -= _value;
        Transfer(msg.sender, _to, _value);
    }
    
    function approve(address _spender, uint256 _value) returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        tokenRecipient spender = tokenRecipient(_spender);
        return true;
    }
    
    function approveAndCall(address _spender, uint256 _value, bytes _extraData) 
        returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(_spender, _value, this, _extraData);
            return true;
        }
    }
    
    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
        if(balanceOf[_from] < _value) throw;
        if(balanceOf[_to] + _value < balanceOf[_to]) throw;
        if(_value > allowance[_from][msg.sender]) throw;
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        allowance[_from][msg.sender] -= _value;
        Transfer(_from, _to, _value);
        return true;
    }
    
    function() {
        throw;
    }
}
    
contract MyAdvancedToken is owned, token {
    uint256 public sellPrice;
    uint256 public buyPrice;
    uint256 public totalSupply;
    
    mapping (address => bool) public frozenAccount;
    
    event FrozenFunds(address target, bool frozen);
    
    function MyAdvancedToken(uint256 initialSupply, string tokenName, uint8 decimalUnits,
        string tokenSymbol, address centralMiner) token (initialSupply, tokenName, decimalUnits, tokenSymbol) {
        if(centralMiner != 0) owner = centralMiner;
        balanceOf[owner] = initialSupply;
    }
    
    function transfer(address _to, uint256 _value) {
        if (balanceOf[msg.sender] < _value) throw;
        if (balanceOf[_to] + _value < balanceOf[_to]) throw;
        if (frozenAccount[msg.sender]) throw;
        balanceOf[msg.sender] -= _value;
        balanceOf[_to] += _value;
        Transfer(msg.sender, _to, _value);
    }
    
    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
        if (balanceOf[_from] < _value) throw;
        if (balanceOf[_to] + _value < balanceOf[_to]) throw;
        if (frozenAccount[_from]) throw;
        if (_value > allowance[_from][msg.sender]) throw;
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        allowance[_from][msg.sender] -= _value;
        Transfer(_from, _to, _value);
        return true;
    }
    
    function mintToken(address target, uint256 mintedAmount) onlyOwner {
        balanceOf[target] += mintedAmount;
        totalSupply += mintedAmount;
        Transfer(0, this, mintedAmount);
        Transfer(this, target, mintedAmount);
    }
    
    function freezeAccount(address target, bool freeze) {
        frozenAccount[target] = freeze;
        FrozenFunds(target, freeze);
    }
    
    function setPrices(uint256 newSellPrice, uint256 newBuyPrice) onlyOwner {
        sellPrice = newSellPrice;
        buyPrice = newBuyPrice;
    }
    
    function buy() payable {
        uint amount = msg.value/buyPrice;
        if (balanceOf[this] < amount) throw;
        balanceOf[msg.sender] += amount;
        balanceOf[this] -= amount;
        Transfer(this, msg.sender, amount);
    }
    
    function sell(uint256 amount) payable {
        if (balanceOf[msg.sender] < amount) throw;
        balanceOf[msg.sender] -= amount;
        balanceOf[this] += amount;
        if(!msg.sender.send(amount * sellPrice)) {
            throw;
        } else {
            Transfer(msg.sender, this, amount);
        }
    }
}