Natural numbers from 1 to $$$n$$$ are written on the board. It is required to select some of them so that among the selected numbers there is exactly one pair of neighbors (numbers that differ by one). Determine how many ways this can be done.
For example, for $$$n=4$$$, the answer is 5 — these are the following 5 ways: {1, 2}, {2, 3}, {3, 4}, {1, 2, 4}, {1, 3, 4}.
One integer $$$n$$$ ($$$1 \le n \le 10^6$$$) is given.
Output one integer — the number of ways modulo $$$10^9+7$$$ (that is, the remainder of the number of ways divided by $$$10^9+7$$$).
4
5
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