摘要：
题目描述 Jack and Jill developed a special encryption method, so they can enjoy conversations without worrrying about eavesdroppers. Here is how: let L be 阅读全文
摘要：
题目描述 A pangram is a phrase that includes at least one occurrence of each of the 26 letters, ‘a’. . .‘z’. You’re probably familiar with this one: “The 阅读全文