function endCoinFlip(bytes32 _stack, bytes32 _counterStack, bytes32 _reveal)
  public
  returns (bool) {
      require(stacks[_stack].owner==msg.sender);
      require(stackCounter[_counterStack]==_stack);
      require(counterOfStack[_stack]==_counterStack);
      require(mode[_stack]==2);
      require(uint32(block.number)>commitBlock[_stack]);

      if(keccak256(_reveal)!=commit[_stack]){
        mode[_stack]=1;
        CoinFlipFail(_stack);
        return false;
      }else{
        mode[_stack]=3;
        round[_stack]=1;
        bytes32 pseudoRandomHash = keccak256(_reveal,block.blockhash(commitBlock[_stack]));
        if(uint256(pseudoRandomHash)%2==0){
          lastBlock[_stack]=uint32(block.number);
          lastActor[_stack]=stacks[_counterStack].owner;
          CoinFlipSuccess(_stack,stacks[_stack].owner,true);
        }else{
          lastBlock[_stack]=uint32(block.number);
          lastActor[_stack]=stacks[_stack].owner;
          CoinFlipSuccess(_stack,stacks[_counterStack].owner,false);
        }
        return true;
      }
    }

 event CoinFlipSuccess(bytes32 indexed stack,address whosTurn,bool heads);
 event CoinFlipFail(bytes32 stack);