Can't verify the contract at ftmscan

Hi guys , this is my code .

when I trying to verify the code on ftmscan , it says Error! Unable to generate Contract ByteCode and ABI (General Exception, unable to get compiled [bytecode])

Compiler Warning(s):

ParserError: Source “@openzeppelin/contracts/token/ERC20/ERC20.sol” not found: File import callback not supported
→ myc:4:1:
|
4 | import “@openzeppelin/contracts/token/ERC20/ERC20.sol”
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

But the token already generated in my wallet ? what happen and what should I do ?

:1234: Code to reproduce

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol";
  //import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/extensions/ERC20Burnable.sol";



contract test is ERC20{
    constructor ( uint256  initialSupply) public ERC20 ("test" , "tt"){
        _mint(msg.sender,initialSupply * 10 ** 18);
    }
   
}

:computer: Environment

remix

Please refer to Verify ERC20 token on Etherscan that was deployed through Remix: Step by Step Guide to verify.

You may need to make adjustments as you are on Fantom.