// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

contract SimpleToken {
    string public name = "Elllex";
    string public symbol = "ELX";
    uint256 public totalSupply = 1000000 * 10**decimals();
    uint8 public decimals = 18;
    address public owner;

    mapping(address => uint) public balances;
    mapping(address => mapping(address => uint)) public allowance;

    constructor() {
        owner = msg.sender;
        balances[owner] = totalSupply;
    }

    function transfer(address _to, uint _amount) external returns (bool) {
        require(balances[msg.sender] >= _amount, "Insufficient balance");
        balances[msg.sender] -= _amount;
        balances[_to] += _amount;
        return true;
    }

    function approve(address _spender, uint _amount) external returns (bool) {
        allowance[msg.sender][_spender] = _amount;
        return true;
    }

    function transferFrom(address _from, address _to, uint _amount) external returns (bool) {
        require(allowance[_from][msg.sender] >= _amount, "Not allowed");
 
        require(balances[_from] >= _amount, "Insufficient balance");
        
        balances[_from] -= _amount;
        balances[_to] += _amount;
        
        allowance[_from][msg.sender] -= _amount;
        return true;
    }
}