Georg Cantor proved that rational numbers are enumerable. He uses the following table to prove this proposition:

$1/1$, $1/2$, $1/3$, $1/4$, $1/5$, …

$2/1$, $2/2$, $2/3$, $2/4$, …

$3/1$, $3/2$, $3/3$, …

$4/1$, $4/2$, …

$5/1$, …

…

We number each term in the above table along the anti-diagonals, going back and forth. That is, the first term is $1/1$, then $1/2$, $2/1$, then $3/1$, $2/2$, $1/3$, then $1/4$ …

Input Specification

The input contains an integer $N$ ($1\le N\le {10}^7$).

Output Specification

Output the $N^{\text{th}}$ term in the table.

Sample Input

7

Sample Output

1/4

Problem translated to English by Tommy_Shan.