// SPDX-License-Identifier: MIT

pragma solidity ^0.8.7;

contract BitcoinRally {
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;

    string public constant name = "Bitcoin Rally";
    string public constant symbol = "BR";
    uint8 public constant decimals = 18;
    uint256 private constant _totalSupply = 21_000_000 * (10 ** uint256(decimals));

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

    constructor() {
        _balances[msg.sender] = _totalSupply;
        emit Transfer(address(0), msg.sender, _totalSupply);
    }

    function totalSupply() external pure returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) external view returns (uint256) {
        return _balances[account];
    }

    function transfer(address to, uint256 value) external returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function allowance(address owner, address spender) external view returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 value) external returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transferFrom(address from, address to, uint256 value) external returns (bool) {
        _transfer(from, to, value);
        _approve(from, msg.sender, _allowances[from][msg.sender] - value);
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) external returns (bool) {
        _approve(msg.sender, spender, _allowances[msg.sender][spender] + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) external returns (bool) {
        uint256 currentAllowance = _allowances[msg.sender][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        _approve(msg.sender, spender, currentAllowance - subtractedValue);
        return true;
    }

    function _transfer(address from, address to, uint256 value) internal {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");
        require(value <= _balances[from], "ERC20: transfer amount exceeds balance");

        _balances[from] -= value;
        _balances[to] += value;
        emit Transfer(from, to, value);
    }

    function _approve(address owner, address spender, uint256 value) internal {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = value;
        emit Approval(owner, spender, value);
    }
}

{
  "compilationTarget": {
    "BitcoinRally.sol": "BitcoinRally"
  },
  "evmVersion": "london",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}