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// SPDX-License-Identifier: MIT
pragma solidity ^0.7.1;

contract SimpleToken {
    string public name = "SimpleToken";
    string public symbol = "STK";
    uint8 public decimals = 18;
    uint256 public totalSupply;

mapping(address => uint256) public balanceOf;
    mapping(address => mapping(address => uint256)) public allowance;

event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

// Constructor that sets the initial supply
    constructor(uint256 _initialSupply) {
        totalSupply = _initialSupply * (10 ** uint256(decimals));
        balanceOf[msg.sender] = totalSupply; // Assign all tokens to the contract's creator
    }

function transfer(address _to, uint256 _value) public returns (bool success) {
        require(_to != address(0), "Cannot transfer to the zero address");
        require(balanceOf[msg.sender] >= _value, "Insufficient balance");

balanceOf[msg.sender] -= _value;
        balanceOf[_to] += _value;
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

function approve(address _spender, uint256 _value) public returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_from != address(0), "Cannot transfer from the zero address");
        require(_to != address(0), "Cannot transfer to the zero address");
        require(balanceOf[_from] >= _value, "Insufficient balance");
        require(allowance[_from][msg.sender] >= _value, "Allowance exceeded");

balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        allowance[_from][msg.sender] -= _value;
        emit Transfer(_from, _to, _value);
        return true;
    }
}