Bit Strings

Explanation

In this problem, we need to calculate the total number of possible bit strings of length n.

This is nothing but 2 ^ n. Except, the n can be very large (upto 10 ^ 6), and we need to print the final answer modulo 10 ^ 9 + 7.

So, to solve this, we'll just loop from 1 to n and multiply the answer with 2 in each iteration. And, we'll take the modulo of the answer with 10 ^ 9 + 7 in each iteration.

Code

n = int(input())
ans = 1

for _ in range(n):
    ans *= 2
    ans %= 1000000007

print(ans)