holis.sol

Hello.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.12;

contract Hello
{
    string public hello = "Hola mundo!";

    function setHello(string memory _hello) public
    {
        hello = _hello;
    }

    function getHello() public view returns(string memory)
    {
        return hello;
    }
}

MyToken.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.12;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract MyToken is ERC20
{
    uint MAX_TOKEN = 1_000_000 ether;
    constructor() ERC20("My Token", "TKN")
    {

    }

    function buy() public payable
    {
        require(msg.value == 0.01 ether, "Must pay token value");
        require(totalSupply() + 100 < MAX_TOKEN, "Supply limit reached");
        _mint(msg.sender, 100 ether);
    }
}