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contracts...MyContract3.sol

pragma solidity >=0.7.0 <0.9.0;

contract MyContract {
    uint256 public peopleCount;
    mapping(uint => Person) public people;
    
    address owner;
    
    uint256 openingTime = 1631171503;
    /// uint256 openingTime = 1631171803;
    
    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }
    
    modifier onlyWhileOpen() {
        require(block.timestamp >= openingTime);
        _;
    }
    
    struct Person {
        uint _id;
        string _firstName;
        string _lastName;
    }
    
    constructor() {
        owner = msg.sender;
    }
    
    function addPerson(
        string memory _firstName, 
        string memory _lastName
    ) 
        public 
        // onlyOwner 
        onlyWhileOpen
    {
        incrementCount();
        people[peopleCount] = Person(peopleCount, _firstName, _lastName);
    }
    
    function incrementCount() internal {
        peopleCount += 1;
    }
    
}