pragma solidity ^0.4.8;


  contract ToutiaoERC20 {
      function totalSupply() constant returns (uint256 totalSupply);

      function balanceOf(address _owner) constant returns (uint256 balance);

      function transfer(address _to, uint256 _value) returns (bool success);

      function transferFrom(address _from, address _to, uint256 _value) returns (bool success);

      function approve(address _spender, uint256 _value) returns (bool success);

      function allowance(address _owner, address _spender) constant returns (uint256 remaining);

      event Transfer(address indexed _from, address indexed _to, uint256 _value);

      event Approval(address indexed _owner, address indexed _spender, uint256 _value);
  }

   contract NewOSToken is ToutiaoERC20 {
      string public constant symbol = "NEWOS"; 
      string public constant name = "NewOS Token"; 
      uint8 public constant decimals = 8; 
      uint256 _totalSupply = 10000000000e8; 

      address public owner;

      mapping(address => uint256) balances;

      mapping(address => mapping (address => uint256)) allowed;

      modifier onlyOwner() {
          assert (msg.sender == owner);
          _;
      }

      constructor() {
          owner = msg.sender;
          balances[owner] = _totalSupply;
      }

      function totalSupply() constant returns (uint256 totalSupply) {
          totalSupply = _totalSupply;
      }

      function balanceOf(address _owner) constant returns (uint256 balance) {
          return balances[_owner];
      }

      function transfer(address _to, uint256 _amount) returns (bool success) {
          if (balances[msg.sender] >= _amount 
              && _amount > 0
              && balances[_to] + _amount > balances[_to]) {
              balances[msg.sender] -= _amount;
              balances[_to] += _amount;
              Transfer(msg.sender, _to, _amount);
              return true;
          } else {
              return false;
          }
      }

      function transferFrom(
          address _from,
          address _to,
          uint256 _amount
      ) returns (bool success) {
          if (balances[_from] >= _amount 
              && allowed[_from][msg.sender] >= _amount
              && _amount > 0
              && balances[_to] + _amount > balances[_to]) {
              balances[_from] -= _amount;
              allowed[_from][msg.sender] -= _amount;
              balances[_to] += _amount;
              Transfer(_from, _to, _amount);
              return true;
          } else {
              return false;
          }
      }

      function approve(address _spender, uint256 _amount) returns (bool success) {
          allowed[msg.sender][_spender] = _amount;
          Approval(msg.sender, _spender, _amount);
          return true;
      }

      function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
          return allowed[_owner][_spender];
      }
  }