Four-time cross-country skiing Olympic champion Dario Cologna of Switzerland will end his career after the upcoming season highlighted by the Beijing Games. The 35-year-old skier made the announcement in a short statement issued on Wednesday by the Swiss ski federation. “I have decided to retire after this season,” Cologna said. “I wanted to communicate the decision before the start of the season to have a clear mind and focus 100 per cent on my sporting goals. I am approaching my fourth Olympics and want to attack there.” Cologna will be bidding for an unprecedented fourth gold in a row in th…