pragma solidity ^0.4.25;

interface StandardERC20 {
  function totalSupply() external view returns (uint256);
  function balanceOf(address who) external view returns (uint256);
  function allowance(address owner, address spender) external view returns (uint256);
  function transfer(address to, uint256 value) external returns (bool);
  function approve(address spender, uint256 value) external returns (bool);
  function transferFrom(address from, address to, uint256 value) external returns (bool);

  event Transfer(address indexed from, address indexed to, uint256 value);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) { return 0; }
    uint256 c = a * b;
    require(c / a == b);
    return c;
  }
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0);
    uint256 c = a / b;
    return c;
  }
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    uint256 c = a - b;
    return c;
  }
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a);
    return c;
  }
  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0);
    return a % b;
  }
}

contract EXM101 is StandardERC20 {
  using SafeMath for uint256;
  mapping (address => uint256) private _balances;
  mapping (address => mapping (address => uint256)) private _allowed;

  uint256 private _totalSupply;

  string public name;
  uint8  public decimals;
  string public symbol;
  string public version;

  function () public { revert(); }

  constructor() public {
    name = "EXM101";
    decimals = 18;
    symbol = "EXM";
    version = "V1.0";
    _totalSupply = 789 * 10**uint(6) * 10**uint(decimals);
    _balances[msg.sender] = _totalSupply;
  }

  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }
  function balanceOf(address owner) public view returns (uint256) {
    return _balances[owner];
  }
  function allowance(address owner, address spender) public view returns (uint256) {
    return _allowed[owner][spender];
  }
  function transfer(address to, uint256 value) public returns (bool) {
    _transfer(msg.sender, to, value);
    return true;
  }
  function approve(address spender, uint256 value) public returns (bool) {
    require(spender != address(0));
    _allowed[msg.sender][spender] = value;
    emit Approval(msg.sender, spender, value);
    return true;
  }
  function transferFrom(address from, address to, uint256 value) public returns (bool) {
    _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
    _transfer(from, to, value);
    return true;
  }
  function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
    require(spender != address(0));
    _allowed[msg.sender][spender] = (
    _allowed[msg.sender][spender].add(addedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }
  function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
    require(spender != address(0));
    _allowed[msg.sender][spender] = (
    _allowed[msg.sender][spender].sub(subtractedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }
  function _transfer(address from, address to, uint256 value) internal {
    require(to != address(0));
    _balances[from] = _balances[from].sub(value);
    _balances[to] = _balances[to].add(value);
    emit Transfer(from, to, value);
  }
  function _mint(address account, uint256 value) internal {
    require(account != address(0));
    _totalSupply = _totalSupply.add(value);
    _balances[account] = _balances[account].add(value);
    emit Transfer(address(0), account, value);
  }
  function _burn(address account, uint256 value) internal {
    require(account != address(0));
    _totalSupply = _totalSupply.sub(value);
    _balances[account] = _balances[account].sub(value);
    emit Transfer(account, address(0), value);
  }
  function _burnFrom(address account, uint256 value) internal {
    _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(value);
    _burn(account, value);
  }
}