文文设计了一个关于实数运算的程序，按此程序，输入一个数后，输出的数比输入的数的平方小1，若输入$\sqrt{7}$，则输出的结果为(  )

   The first telephone cards, produced in 1976, were Italian. Five years later the first British card appeared, and now you can buy cards in more than a hundred countries. People usually start collecting cards because they are small and light and you do not need much space for them. It is also a cheap hobby for beginners, although for some people it becomes a serious business. In Paris, for example, there is a market where you can only buy telephone cards, and some cards cost up to ￡4,000.The first Japanese card has a value of about ￡28,000. Most people only see cards with prices like these in their collectors' magazine.