contacts\ToToToken.sol

pragma solidity 0.5.2;

import "./CustomToken.sol";

contract ToToToken is CustomToken {
    uint8 private DECIMALS = 5; //자리수
    uint256 private MAX_TOKEN_COUNT = 20000000000;   // 총 토큰 개수
    uint256 private MAX_SUPPLY = MAX_TOKEN_COUNT * (10 ** uint256(DECIMALS)); //총 발행량
    uint256 private INITIAL_SUPPLY = MAX_SUPPLY * 1 / 10; //초기 공급량

    bool private issued = false;

    constructor()
        CustomToken("ToToToken", "TOTO", DECIMALS, MAX_SUPPLY)
        public {
            require(issued == false);
            super.mint(msg.sender, INITIAL_SUPPLY);
            issued = true;
    }

}

contracts\CustomToken.sol

pragma solidity 0.5.2;

import "openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";
import "openzeppelin-solidity/contracts/token/ERC20/ERC20Burnable.sol";
import "openzeppelin-solidity/contracts/token/ERC20/ERC20Capped.sol";
import "openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol";

contract CustomToken is ERC20, ERC20Detailed, ERC20Capped, ERC20Burnable {
    constructor(
            string memory _name,
            string memory _symbol,
            uint8 _decimals,
            uint256 _maxSupply
        )
        ERC20Burnable()
        ERC20Capped(_maxSupply)
        ERC20Detailed(_name, _symbol, _decimals)
        ERC20()
        public {
            
        }