| Almaty Code Cup 2024 |
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| Finished |
fractal loves geometry, so let's place him in a space he's familiar with, a two-dimensional plane. Initially, fractal is at coordinate O(0, 0) and facing the Ox axis. He was given a task, a piece of paper, and an even number $$$n$$$ $$$(4 \le n \le 10^6)$$$, the reason and purpose of which few know, but such is fate. He needs to perform exactly n operations, each operation happens as follows:
If after performing all operations, fractal ends up at coordinate O(0, 0) and facing the Ox axis, and also never, except for the very last moment of the last operation, was at a coordinate he visited before, then the resulting record on the paper will be called the «answer» to the task.
But since fractal loves to count everything and Catalan numbers, he wanted to count how many «answers» he could get. Since the answer can be very large, output it modulo $$$10^9 + 7$$$.
The first line contains a single even number $$$n$$$ $$$(4 \le n \le 10^6)$$$.
Output a single number, the number of «answers» modulo $$$10^9 + 7$$$.
4
2
6
12
Note that after a series of operations:
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