function getWinSlot(uint256 _keyNumber)
        public
        view
        returns(uint256)
    {
        
        uint256 _to = slot.length - 1;
        uint256 _from = round[curRoundId-1].slotSum + 1; 
        uint256 _pivot;
        
        uint256 _pivotTo;
        
        while (_from <= _to) {
            _pivot = (_from + _to) / 2;
            _pivotTo = slot[_pivot].tNumberTo;
            if (isWinSlot(_pivot, _keyNumber)) return _pivot;
            if (_pivotTo < _keyNumber) { 
                _from = _pivot + 1;
            } else { 
                _to = _pivot - 1;
            }
        }
        return _pivot; 
    }