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HelloWorld.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.1;

/// @notice Hello World contract
contract HelloWorld {
    /// @notice state variable to store the number
    uint256 intToStore;

    /**
     * @notice Stores specified number in contract
     * @param _number number which needs to be set in contract intToStore variable
     */
    function storeNumber(uint256 _number) external {
        intToStore = _number;
    }

    /**
     * @notice Retrieves the number which is stored in contract and can be updated using storeNumber function
     */
    function retrieveNumber() external view returns (uint256) {
        return intToStore;
    }
}