pragma solidity ^0.5.9;

/**
 * Math operations with safety checks
 */
library SafeMath {
function safeAdd(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }


    function safeSub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        uint256 c = a - b;

        return c;
    }

    function safeMul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    function safeDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, "SafeMath: division by zero");
        uint256 c = a / b;

        return c;
    }

    function safeMod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0, "SafeMath: modulo by zero");
        return a % b;
    }
}

contract FitToken {
    using SafeMath for uint256;
    string public name;
    string public symbol;
    uint8 public decimals;
    uint256 public totalSupply;
	address public owner;

    /* This creates an array with all balances */
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    /* This generates a public event on the blockchain that will notify clients */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /* This notifies clients about the amount burnt */
    event Burn(address indexed from, uint256 value);

    /* Initializes contract with initial supply tokens to the creator of the contract */
    constructor(
        uint256 initialSupply,
        string memory tokenName,
        uint8 decimalUnits,
        string memory tokenSymbol
        ) public {
        balanceOf[msg.sender] = initialSupply;              // Give the creator all initial tokens
        totalSupply = initialSupply;                        // Update total supply
        name = tokenName;                                   // Set the name for display purposes
        symbol = tokenSymbol;                               // Set the symbol for display purposes
        decimals = decimalUnits;                            // Amount of decimals for display purposes
		owner = msg.sender;
    }

    /* Send coins */
    function transfer(address _to, uint256 _value) public {
        require(_to != address(0), "Cannot use zero address");
        require(_value > 0, "Cannot use zero value");

        require (balanceOf[msg.sender] >= _value, "Balance not enough");         // Check if the sender has enough
        require (balanceOf[_to] + _value >= balanceOf[_to], "Overflow" );        // Check for overflows
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value); // Subtract from the sender
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);               // Add the same to the recipient
        emit Transfer(msg.sender, _to, _value);                                  // Notify anyone listening that this transfer took place
    }

    function approve(address _spender, uint256 _value) public
        returns (bool success) {
		require (_value > 0, "Cannot use zero");
        allowance[msg.sender][_spender] = _value;
        return true;
    }

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_to != address(0), "Cannot use zero address");
		require(_value > 0, "Cannot use zero value");
		require( balanceOf[_from] >= _value, "Balance not enough" );
        require( balanceOf[_to] + _value > balanceOf[_to], "Cannot overflows" );
        require( _value <= allowance[_from][msg.sender], "Cannot over allowance" );
        balanceOf[_from] = SafeMath.safeSub(balanceOf[_from], _value);
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);
        allowance[_from][msg.sender] = SafeMath.safeSub(allowance[_from][msg.sender], _value);
        emit Transfer(_from, _to, _value);
        return true;
    }

}