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Eva would like to make a string of beads with her favorite colors so she went to a small shop to buy some beads. There were many colorful strings of b 阅读全文
摘要：
Among all the factors of a positive integer N, there may exist several consecutive numbers. For example, 630 can be factored as 3×5×6×7, where 5, 6, a 阅读全文
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On a broken keyboard, some of the keys are worn out. So when you type some sentences, the characters corresponding to those keys will not appear on sc 阅读全文
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People often have a preference among synonyms of the same word. For example, some may prefer "the police", while others may prefer "the cops". Analyzi 阅读全文