Cantor's Table

Problem Background

Special for beginners, ^_^

Problem Description

One of the famous proofs in modern mathematics is Georg Cantor's proof that the rational numbers are enumerable. He proved this proposition using the following table:

We number each entry of the above table in a zigzag (Z-shaped) order. The first entry is $1/1$, then $1/2$, $2/1$, $3/1$, $2/2$, and so on.

Given $N$, find the $N$-th entry of the table.

Input Format

One integer $N$ ($1 \le N \le 10^7$).

Output Format

A fraction, the $N$-th entry of the table.

Sample Input

7

Sample Output

1/4

Constraints

Time limit: 1s, memory limit: 1024KiB for each test case.