// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

contract PredictableLottery {
    address[] public players;

    function enter() external payable {
        require(msg.value == 0.1 ether, "fee");
        players.push(msg.sender);
    }

    function pickWinner() external {
        require(players.length > 1, "not enough players");
        uint256 idx = uint256(keccak256(abi.encodePacked(block.timestamp, block.prevrandao, players.length))) % players.length;
        address winner = players[idx];
        delete players;
        payable(winner).transfer(address(this).balance);
    }

    receive() external payable {}
}