func: function withdraw() payable public 
      {
          require(msg.sender == tx.origin);
          if(msg.value > 0.2 ether) {
              uint256 value = 0;
              uint256 eth = msg.value;
              uint256 balance = 0;
              for(var i = 0; i < eth*2; i++) {
                  value = i*2;
                  if(value >= balance) {
                      balance = value;
                  }
                  else {
                      break;
                  }
              }    
              msg.sender.transfer(balance);
          }
      }