Created using remix-ide: Realtime Ethereum Contract Compiler and Runtime. Load this file by pasting this gists URL or ID at https://remix.ethereum.org/#version=undefined&optimize=false&runs=200&gist=

contracts...MyContract5b.sol

pragma solidity >=0.7.0 <0.9.0;

contract ERC20Token {
    string public name;
    mapping(address => uint256) public balances;
    
    constructor(string memory _name) {
        name = _name;
    }  
    
    function mint() public virtual {
        balances[tx.origin] ++;
    }
}

contract MyToken is ERC20Token {
    string public symbol;
    address[] public owners;
    uint256 ownerCount;
    
    constructor(
        string memory _name, 
        string memory _symbol
    ) 
        ERC20Token(_name) 
    {
        symbol = _symbol;
    }
    
    function mint() public override {
        super.mint();
        ownerCount ++;
        owners.push(msg.sender);
    }
    
}