Your librarian has a 2-row bookshelf that can contain N books in each row. She wants to know the number of ways that she can fill the bookshelf with red-colored books and blue-colored books such that no 2 red-colored books are adjacent to each other (horizontally or vertically). Input: the integer, N (1<=N<=2^1024) Output: the number of ways you can place red-colored books and blue-colored books onto a N-column bookshelf. Since this number might be really big, output it mod 10^9+7. Example: Input: 2 Your valid bookshelf layouts are: ``` BB BB BB BR BR BB RB BB BB RB RB BR BR RB ``` Therefore, Output: 7