Number of bit-strings
Given an integer
n, you are asked to calculate the number of different bit-strings of length n. Bit strings are strings that only have 0s and 1s.Input
The only line of the input contains a single integer
n (1 ≤ n ≤ 30)Output
The program should print the number of bit strings of length
n.Examples
Input | Output |
3 | 8 |
4 | 16 |
Explanation
3 → 000, 001, 010, 011, 100, 101, 110, 111 ⇒ 8 different bit-strings.
4 → 000, 0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111 ⇒ 16 different bit-strings.
Constraints
Time limit: 2 seconds
Memory limit: 512 MB
Output limit: 1 MB