LOS ANGELES (Reuters) - "Mission: Impossible III," the first big action film of the summer, opened disappointingly at the weekend box office in North American, despite a whirlwind publicity tour by its pricey star, Tom Cruise. The spy thriller sold $48 million worth of tickets in its first three days in theaters across the United States and Canada, distributor Paramount Pictures said on Sunday. The Viacom Inc.-owned studio said the figure was within its expectations of a bow in the $50 million range, but it was gratified by the international showing, where it earned $70 million after opening virtually everywhere...