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 \leq N \leq 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.