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CSES Problem Set

Bit Strings


Task | Statistics


CSES - Bit StringsCSES - Bit Strings

Time limit:1.00 s Memory limit:512 MB

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 $10^9+7$.

Constraints
Example

Input:
3

Output:
8