They are the sort of friends who are so close that they trust each other with their lives.If one falls，the other is there to catch him. They are Wellman，whose legs were permanently injured nine years ago in a rock-climbing accident，and Corbett，an experienced rock climber.Together，they climbed up Half Dome，the famous 2,000-foot rock in the Yosemite National Park，through one of the most difficult routes.

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