#2438. 位串数量Bit Strings

    ID: 2438 Type: FileIO (bit) 1000ms 256MiB Tried: 73 Accepted: 12 Difficulty: 8 Uploaded By: Tags>其他数学CSES Introductory Problems

位串数量Bit Strings

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+710^9+7

Constraints

  • 1n10181≤n≤10^{18}

Example

3
8