Smart Contract BitcoinSet

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract BitcoinSet {
    string public name = "BitcoinSet";
    string public symbol = "₿S";
    uint8 public decimals = 18;
    uint256 public totalSupply = 2500000 * 10**decimals;
    
    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() {
        balanceOf[msg.sender] = totalSupply;
    }
    
    function transfer(address to, uint256 value) public returns (bool) {
        require(balanceOf[msg.sender] >= value);
        balanceOf[msg.sender] -= value;
        balanceOf[to] += value;
        emit Transfer(msg.sender, to, value);
        return true;
    }
    
    function approve(address spender, uint256 value) public returns (bool) {
        allowance[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }
}