/** * Source Code first verified at https://etherscan.io on Wednesday, May 8, 2019 (UTC) */ pragma solidity >=0.4.22 <0.6.0; /** * @title SafeMath * @dev Unsigned math operations with safety checks that revert on error. */ library SafeMath { /** * @dev Multiplies two unsigned integers, reverts on overflow. */ function mul(uint256 a, uint256 b) internal pure returns (uint256) { // Gas optimization: this is cheaper than requiring 'a' not being zero, but the // benefit is lost if 'b' is also tested. // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522 if (a == 0) { return 0; } uint256 c = a * b; require(c / a == b, "SafeMath: multiplication overflow"); return c; } /** * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero. */ function div(uint256 a, uint256 b) internal pure returns (uint256) { // Solidity only automatically asserts when dividing by 0 require(b > 0, "SafeMath: division by zero"); uint256 c = a / b; // assert(a == b * c + a % b); // There is no case in which this doesn't hold return c; } /** * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend). */ function sub(uint256 a, uint256 b) internal pure returns (uint256) { require(b <= a, "SafeMath: subtraction overflow"); uint256 c = a - b; return c; } /** * @dev Adds two unsigned integers, reverts on overflow. */ function add(uint256 a, uint256 b) internal pure returns (uint256) { uint256 c = a + b; require(c >= a, "SafeMath: addition overflow"); return c; } /** * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo), * reverts when dividing by zero. */ function mod(uint256 a, uint256 b) internal pure returns (uint256) { require(b != 0, "SafeMath: modulo by zero"); return a % b; } } /// Buy OurERC20 don't miss the oportunity contract OurERC20 { using SafeMath for uint256; string _name; string _symbol; mapping (address => uint256) _balances; uint256 _totalSupply; uint8 private _decimals; event Transfer(address indexed from, address indexed to, uint tokens); constructor() public { _name = "HOLA"; _symbol = "HL"; _decimals = 0; } function decimals() public view returns(uint8) { return _decimals; } function totalSupply() public view returns (uint256) { return _totalSupply; } function name() public view returns (string memory) { return _name; } function symbol() public view returns (string memory) { return _symbol; } function mint(uint256 amount) public payable { require(msg.value == amount.mul(0.006 ether)); _balances[msg.sender] = _balances[msg.sender].add(amount); _totalSupply = _totalSupply + amount; } function burn(uint256 amount) public { require(_balances[msg.sender] == amount); _balances[msg.sender] = _balances[msg.sender].sub(amount); msg.sender.transfer(amount.mul(0.006 ether)); _totalSupply = _totalSupply - amount; } function transfer(address _to, uint256 value) public returns (bool success) { require(_balances[msg.sender] >= value); _balances[msg.sender] = _balances[msg.sender].sub(value); _balances[_to] = _balances[_to].add(value); emit Transfer(msg.sender, _to, value); return true; } }