MorganStanley (MGSTL)

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

/**
 * @title MGSTL Token
 * @dev Simple ERC20 Token with fixed supply
 */
contract MGSTL {
    string public name;
    string public symbol;
    uint8 public decimals;
    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() {
        name = "MorganStanley";
        symbol = "MGSTL";
        decimals = 18;
        totalSupply = 1000000000 * 10**decimals; // 1 billion tokens
        
        balanceOf[msg.sender] = totalSupply;
        emit Transfer(address(0), msg.sender, totalSupply);
    }
    
    function transfer(address to, uint256 value) external returns (bool) {
        require(to != address(0), "Invalid 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) external returns (bool) {
        require(spender != address(0), "Invalid address");
        
        allowance[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }
    
    function transferFrom(address from, address to, uint256 value) external returns (bool) {
        require(from != address(0), "Invalid address");
        require(to != address(0), "Invalid address");
        require(balanceOf[from] >= value, "Insufficient balance");
        require(allowance[from][msg.sender] >= value, "Insufficient allowance");
        
        balanceOf[from] -= value;
        balanceOf[to] += value;
        allowance[from][msg.sender] -= value;
        
        emit Transfer(from, to, value);
        return true;
    }
    
    function burn(uint256 value) external returns (bool) {
        require(balanceOf[msg.sender] >= value, "Insufficient balance");
        
        balanceOf[msg.sender] -= value;
        totalSupply -= value;
        
        emit Transfer(msg.sender, address(0), value);
        return true;
    }
}