Polo the Penguin and XOR operation

题意翻译

对于数列 $P=P_0,P_1,\cdots,P_n$（仅由 $0$ 到 $n$ 构成，每个数字只出现一次），求出 $(0 \oplus P_0)+(1 \oplus P_1)+\cdots+(n \oplus P_n)$ 的最大值。

题目描述

Little penguin Polo likes permutations. But most of all he likes permutations of integers from $ 0 $ to $ n $ , inclusive. For permutation $ p=p_{0},p_{1},...,p_{n} $ , Polo has defined its beauty — number . Expression  means applying the operation of bitwise excluding "OR" to numbers $ x $ and $ y $ . This operation exists in all modern programming languages, for example, in language C++ and Java it is represented as "^" and in Pascal — as "xor". Help him find among all permutations of integers from $ 0 $ to $ n $ the permutation with the maximum beauty.

输入输出格式

输入格式

The single line contains a positive integer $ n $ ( $ 1<=n<=10^{6} $ ).

输出格式

In the first line print integer $ m $ the maximum possible beauty. In the second line print any permutation of integers from $ 0 $ to $ n $ with the beauty equal to $ m $ . If there are several suitable permutations, you are allowed to print any of them.

输入输出样例

输入样例 #1

4

输出样例 #1

20
0 2 1 4 3