themes.sol

pragma solidity ^0.5.2;

contract TheTimes {

    uint256 public TotalSupply;
    uint256 public MaxSupply = 21000;
    uint256 public Price;

    address[] public Hodlers;

    constructor() public {
        Price = 1000 finney;
        TotalSupply = 0;
    }

    function buy() public payable returns (uint256) {
        require(msg.value == Price, "Incorrect price");
        require(TotalSupply < MaxSupply, "All sold out");

        Hodlers.push(msg.sender);

        TotalSupply += 1;
        Price += 1000 finney;

        return Hodlers.length;
    }
}