ERC20.sol

pragma solidity ^0.7.0;

contract SafeMath {
    function safeAdd(uint a, uint b) public pure returns (uint c) {
        c = a + b;
        require(c >= a);
    }
    function safeSub(uint a, uint b) public pure returns (uint c) {
        require(b <= a);
        c = a - b;
    }
    function safeMul(uint a, uint b) public pure returns (uint c) {
        c = a * b;
        require(a == 0 || c / a == b);
    }
    function safeDiv(uint a, uint b) public pure returns (uint c) {
        require(b > 0);
        c = a / b;
    }
}



interface ERC20Interface {
    function totalSupply() external returns (uint);
    function balanceOf(address tokenOwner)  external returns (uint balance);
    function allowance(address tokenOwner, address spender) external returns (uint remaining);
    function transfer(address to, uint tokens) external returns (bool success);
    function approve(address spender, uint tokens) external returns (bool success);
    function transferFrom(address from, address to, uint tokens) external returns (bool success);

    event Transfer(address indexed from, address indexed to, uint tokens);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}



contract Ownership {
    address public owner;
    address public newOwner;

    event OwnershipTransferred(address indexed _from, address indexed _to);

    constructor()  {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address _newOwner) public onlyOwner {
        newOwner = _newOwner;
    }
    
    
    function acceptOwnership() public {
        require(msg.sender == newOwner);
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
        newOwner = address(0);
    }
}



contract MyERC20Token is ERC20Interface, Ownership, SafeMath {
    string public symbol;
    string public  name;
    uint8 public decimals;
    uint public _totalSupply;

    mapping(address => uint) balances;
    mapping(address => mapping(address => uint)) allowed;



    constructor()  {
        symbol = "SKA";
        name = "SKA's Token";
        decimals = 18;
        _totalSupply = 10000000000000000000000000;
    }



    function totalSupply() public override view returns (uint) {
        return _totalSupply;
    }



    function balanceOf(address tokenOwner) public view override returns (uint balance) {
        return balances[tokenOwner];
    }



    function transfer(address to, uint tokens) public override returns (bool success) {
        require(balances[msg.sender] >= tokens);
        balances[msg.sender] = safeSub(balances[msg.sender], tokens);
        balances[to] = safeAdd(balances[to], tokens);
        emit Transfer(msg.sender, to, tokens);
        return true;
    }



    function approve(address spender, uint tokens) public override returns (bool success) {
        allowed[msg.sender][spender] = tokens;
        emit Approval(msg.sender, spender, tokens);
        return true;
    }



    function transferFrom(address from, address to, uint tokens) public override returns (bool success) {
        require(allowed[from][to] >= tokens);
        balances[from] = safeSub(balances[from], tokens);
        allowed[from][msg.sender] = safeSub(allowed[from][msg.sender], tokens);
        balances[to] = safeAdd(balances[to], tokens);
        emit Transfer(from, to, tokens);
        return true;
    }



    function allowance(address tokenOwner, address spender) public view override returns (uint remaining) {
        return allowed[tokenOwner][spender];
    }


    fallback () external payable {
        revert();
    }

}