Provide a response to the following question: What are the key benefits of using cloud computing? Your answer must contain at least 3 placeholders represented by square brackets, such as [benefit1]. Your response should contain at least 4 sentences. Highlight at least 2 sections in your answer with markdown, i.e. *highlighted section*. Include keywords [scalability], [cost-efficiency], [reliability], [flexibility] in the response. At the end of your response, please explicitly add a postscript starting with *P.S.*.

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