function checkN(uint256 _stage, uint256 _position)
    internal
    view
    returns (uint8)  {
        require(_stage <= SafeMath.sub(numberOfStages, 1));
        uint8 count = 0;
        if (isNumberCalled(_stage, stages[_stage].playerCards[msg.sender][_position].N.N1)) {count = SafeMath.add2(count, 1);}
        if (isNumberCalled(_stage, stages[_stage].playerCards[msg.sender][_position].N.N2)) {count = SafeMath.add2(count, 1);}
        if (isNumberCalled(_stage, stages[_stage].playerCards[msg.sender][_position].N.N3)) {count = SafeMath.add2(count, 1);}
        if (isNumberCalled(_stage, stages[_stage].playerCards[msg.sender][_position].N.N4)) {count = SafeMath.add2(count, 1);}
        if (isNumberCalled(_stage, stages[_stage].playerCards[msg.sender][_position].N.N5)) {count = SafeMath.add2(count, 1);}
        return count;
    }