URI Online Judge | 2337

Pro Ability

By Levi da Silva Lima, UEA BR Brazil

Timelimit: 1

Francisco is a big fan of the game "Let’s flip a coin" and loves to play it with your lucky coin, but Francisco has some playing conditions. He always chooses "Head" and in each round of the game can be multiple currency pitches. Another thing is that Francis hates when the currency falls with the "Tail" face in two consecutive pitches. Curious, Francisco wanted to know what is the probability that in a game of "Let’s flip a coin" will not occur "Tail" in two consecutive shots, however, as he only likes to play, he asked you to do a program that calculates it to him.

Input

The input contains several test cases, each line of input will contain an integer N (0<N≤40) representing the amount of pitches in a single match.

Output

For each input line should be only one output line. The output should contain the probability of no consecutive "Tails". The answer must be in the form of irreducible fraction.

Input Sample Output Sample

1

10

1/1

9/64