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Time limit 2000/4000/4000/4000 ms. Memory limit 65000/65000/65000/65000 Kb.
Difficulty Alpha
Your task is to calculate the number of bit strings of length n.
For example, if n=3, the correct answer is 8, because the possible bit strings
are 000, 001, 010, 011, 100, 101, 110, and 111.
Input
The only input line has an integer n.
Output
Print the result modulo 109+7.
Constraints
1≤n≤106
Example
Input:
3
Output:
8
Для отправки решений необходимо выполнить вход.
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