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 $000, 001, 010, 011, 100, 101, 110, and 111$.

The only input line has an integer $n$.

Print the result modulo $10^9+7$. $$ 1 \leq n \leq 10^6 $$