OpenJudge

9290:Pku2680 Computer Transformation

总时间限制:
1000ms
内存限制:
131072kB
描述

A sequence consisting of one digit, the number 1 is initially written into a computer. At each successive time step, the computer simultaneously tranforms each digit 0 into the sequence 1 0 and each digit 1 into the sequence 0 1. So, after the first time step, the sequence 0 1 is obtained; after the second, the sequence 1 0 0 1, after the third, the sequence 0 1 1 0 1 0 0 1 and so on.

How many pairs of consequitive zeroes will appear in the sequence after n steps?

输入

Every input line contains one natural number n (0 < n <= 1000).

输出

For each input n print the number of consequitive zeroes pairs that will appear in the sequence after n steps.

样例输入
2
3
样例输出
1
1
全局题号
9290
添加于
2016-06-16
提交次数
203
尝试人数
107
通过人数
90