// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;
 
// https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.0.0/contracts/token/ERC20/IERC20.sol
interface IERC20 {
   function totalSupply() external view returns (uint);
 
   function balanceOf(address account) external view returns (uint);
 
   function transfer(address recipient, uint amount) external returns (bool);
 
   function allowance(address owner, address spender) external view returns (uint);
 
   function approve(address spender, uint amount) external returns (bool);
 
   function transferFrom(
       address sender,
       address recipient,
       uint amount
   ) external returns (bool);
 
   event Transfer(address indexed from, address indexed to, uint value);
   event Approval(address indexed owner, address indexed spender, uint value);
}
 
 
 
contract ERC20 is IERC20 {
   uint public totalSupply;
   mapping(address => uint) public balanceOf;
   mapping(address => mapping(address => uint)) public allowance;
   string public name = "Solidity by Example";
   string public symbol = "PAHLAVI";
   uint8 public decimals = 18;
 
   function transfer(address recipient, uint amount) external returns (bool) {
       balanceOf[msg.sender] -= amount;
       balanceOf[recipient] += amount;
       emit Transfer(msg.sender, recipient, amount);
       return true;
   }
 
   function approve(address spender, uint amount) external returns (bool) {
       allowance[msg.sender][spender] = amount;
       emit Approval(msg.sender, spender, amount);
       return true;
   }
 
   function transferFrom(
       address sender,
       address recipient,
       uint amount
   ) external returns (bool) {
       allowance[sender][msg.sender] -= amount;
       balanceOf[sender] -= amount;
       balanceOf[recipient] += amount;
       emit Transfer(sender, recipient, amount);
       return true;
   }
 
   function mint(uint amount) external {
       balanceOf[msg.sender] += amount;
       totalSupply += amount;
       emit Transfer(address(0), msg.sender, amount);
   }
 
   function burn(uint amount) external {
       balanceOf[msg.sender] -= amount;
       totalSupply -= amount;
       emit Transfer(msg.sender, address(0), amount);
   }
}