CF288C Polo the Penguin and XOR operation

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.

The single line contains a positive integer $ n $ ( $ 1

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.