将一个字符串str的内容颠倒过来，并输出。str的长度不超过100个字符。

字符串的输入输出处理。

Consider the following algorithm to generate a sequence of numbers. Start with an integer n. If n is even, divide by 2. If n is odd, multiply by 3 and add 1. Repeat this process with the new value of n, terminating when n = 1. For example, the following sequen…

Your task is to calculate the sum of some integers.

Your task is to Calculate a + b.

Your task is to calculate the sum of some integers