Can you please provide a detailed summary of the key events that led to the formation of the United Nations? Your response should contain at least 5 sentences. Highlight at least 2 sections in your answer with markdown, i.e. *highlighted section*. At the end of your response, please explicitly add a postscript starting with *P.S.*. Your entire response should be in English, and in all lowercase letters. no capital letters are allowed.
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