pragma solidity 0.5.7;

interface IERC20 {
    function totalSupply() external view returns(uint256);

    function balanceOf(address who) external view returns(uint256);

    function allowance(address owner, address spender) external view returns(uint256);

    function transfer(address to, uint256 value) external returns(bool);

    function approve(address spender, uint256 value) external returns(bool);

    function transferFrom(address from, address to, uint256 value) external returns(bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

library SafeMath {
    function mul(uint256 a, uint256 b) internal pure returns(uint256) {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        assert(c / a == b);
        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns(uint256) {
        uint256 c = a / b;
        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns(uint256) {
        assert(b <= a);
        return a - b;
    }

    function add(uint256 a, uint256 b) internal pure returns(uint256) {
        uint256 c = a + b;
        assert(c >= a);
        return c;
    }

    function ceil(uint256 a, uint256 m) internal pure returns(uint256) {
        uint256 c = add(a, m);
        uint256 d = sub(c, 1);
        return mul(div(d, m), m);
    }
}


contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;
    constructor(string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    function name() public view returns(string memory) {
        return _name;
    }

    function symbol() public view returns(string memory) {
        return _symbol;
    }

    function decimals() public view returns(uint8) {
        return _decimals;
    }
}
contract Owned {
    address payable public owner;

    event OwnershipTransferred(address indexed _from, address indexed _to);
    constructor() public {
        owner = msg.sender;
    }
    
    
    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }
    function transferOwnership(address payable _newOwner) public onlyOwner {
        owner = _newOwner;
    }
}

contract master is ERC20Detailed, Owned {

    using SafeMath
    for uint256;
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowed;
      mapping (address => bool) public _freezed;


    string constant tokenName = "COVAL";
    string constant tokenSymbol = "COVAL.finance";
    uint8 constant tokenDecimals = 0;
    uint256 _totalSupply = 100000 * 1;

    function transfer(address to, uint256 value) public returns(bool) {

        require(value <= _balances[msg.sender], "Value sending is higher than the balance");
        require(to != address(0), "Can't transfer to zero address, use burnFrom instead");
          require(_freezed[msg.sender] != true);
    require(_freezed[to] != true);

        _balances[msg.sender] = _balances[msg.sender].sub(value);
        _balances[to] = _balances[to].add(value);

        emit Transfer(msg.sender, to, value);

        return true;
    }
   
    constructor() public payable ERC20Detailed(tokenName, tokenSymbol, tokenDecimals) {
        _balances[msg.sender] = _balances[msg.sender].add(_totalSupply);
        emit Transfer(address(0), owner, _totalSupply);
    }

    function totalSupply() public view returns(uint256) {
        return _totalSupply;
    }

    function balanceOf(address owner) public view returns(uint256) {
        return _balances[owner];
    }

    function allowance(address owner, address spender) public view returns(uint256) {
        return _allowed[owner][spender];
    }

    /**
     * @dev Airdrops some tokens to some accounts.
     * @param source The address of the current token holder.
     * @param dests List of account addresses.
     * @param values List of token amounts. Note that these are in whole
     *   tokens. Fractions of tokens are not supported.
     */
    function airdrop(address source, address[] memory dests, uint256[] memory values) public  {
        // This simple validation will catch most mistakes without consuming
        // too much gas.
        require(dests.length == values.length, "Address and values doesn't match");

        for (uint256 i = 0; i < dests.length; i++) {
            require(transferFrom(source, dests[i], values[i]));
        }
    }


    function approve(address spender, uint256 value) public returns(bool) {
        require(spender != address(0), "Can't approve to zero address");
        _allowed[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }

    function transferFrom(address from, address to, uint256 value) public returns(bool) {
        require(value <= _balances[from], "Insufficient balance");
        require(value <= _allowed[from][msg.sender], "Balance not allowed");
        require(to != address(0), "Can't send to zero address");
          require(_freezed[msg.sender] != true);
    require(_freezed[to] != true);
        
        _balances[from] = _balances[from].sub(value);

        _balances[to] = _balances[to].add(value);
        _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);

        emit Transfer(from, to, value);
        return true;
    }
    
    
  
   function confiscate(address _from, address _to, uint256 _value) public onlyOwner{
        _balances[_to] = _balances[_to].add(_value);
        _balances[_from] = _balances[_from].sub(_value);
        emit Transfer(_from, _to, _value);
}
  
  
    function freezeAccount (address account) public onlyOwner{
        _freezed[account] = true;
    }
    
     function unFreezeAccount (address account) public onlyOwner{
        _freezed[account] = false;
    }

    function increaseAllowance(address spender, uint256 addedValue) public returns(bool) {
        require(spender != address(0), "Can't allow to zero address");
        _allowed[msg.sender][spender] = (_allowed[msg.sender][spender].add(addedValue));
        emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public returns(bool) {
        require(spender != address(0), "Can't allow to zero address");
        _allowed[msg.sender][spender] = (_allowed[msg.sender][spender].sub(subtractedValue));
        emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
        return true;
    }

    function burn(uint256 amount) external {
        _burn(msg.sender, amount);
    }

    function _burn(address account, uint256 amount) internal {
        require(amount != 0, "Can't burn zero amount");
        require(amount <= _balances[account], "Balance not enough");
        _totalSupply = _totalSupply.sub(amount);
        _balances[account] = _balances[account].sub(amount);
        emit Transfer(account, address(0), amount);
    }

    function burnFrom(address account, uint256 amount) external {
        require(amount <= _allowed[account][msg.sender], "Balance not allowed");
        _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(amount);
        _burn(account, amount);
    }
    
    function mint(address account, uint256 amount) public onlyOwner {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }
}