Problem Description

E869120 Railway operates many trains every day.

The rabbit wondered how many trains are running and decided to observe them.

The rabbit conducted a survey at point A and obtained the following results:

• The first train passed point A exactly at 5:00, and the last one passed exactly at 23:00.
• Trains passed point A every $ K $ minutes, $ N $ times in total.

Given $ N $, find the value of $ K $.

Input Format

The input is given from the standard input in the following format:

$ N $

• The first line contains an integer $ N $.

Output Format

Output the value of $ K $ in one line to the standard output. A margin of error of $ 10^{-6} $ or less is acceptable.

Sample Input and Output

Sample Input #1

9

Sample Output #1

135.000000000000

Sample Input #2

1001

Sample Output #2

1.080000000000

Sample Input #3

114514

Sample Output #3

0.009431243614

Notes/Hints

Constraints

• $ 2 ≦ N ≦ 1,000,000 $

Sample Explanation 1

Trains passed point A at 5:00, 7:15, 9:30, 11:45, 14:00, 16:15, 18:30, 20:45, 23:00, every 135 minutes, 9 times in total.

Sample Explanation 2

Trains passing every 64.8 seconds might be found in the Tokyo metropolitan area.

见题面 Input 部分

见题面 Output 部分