Thimbles

In the game "3 Thimbles," the probability of correctly guessing the thimble hiding the seed is 0.4. Each correct guess earns the player 2 lars, while each incorrect guess results in a loss of 1 lar.

Your task is to calculate the probability that the player will run out of funds, starting with an initial amount of N lars. Once the player's funds are depleted, they can no longer continue playing.

Input

The input consists of a single line containing an integer N (0 ≤ N ≤ 50), representing the initial amount of lars the player has.

Output

Output a single line with the probability that the player will run out of funds, rounded to seven decimal places.

Examples