In this picture released by mountain guide Adrian Ballinger of Alpenglow Expeditions and taken Saturday, May 18, 2013, Tibetan Buddhist prayer flags are seen on the summit of Mount Everest, in the Khumbu region of the Nepal Himalayas. Nepal celebrated the 60th anniversary of the conquest of Mount Everest on Wednesday, May 29, 2013, by honoring climbers who followed in the footsteps of Edmund Hillary and Tenzing Norgay.(AP Photo/Alpenglow Expeditions)

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