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contracts...MainToken.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity >=0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";


contract MainToken is ERC20 {
    constructor(uint _initialSupply) ERC20("MainToken", "MT") {
        // Assume that msg.sender is ManagerContract.
        _mint(msg.sender, _initialSupply);
    }
}