Duelists#1319
Two duelists decided to settle their relationship in a duel. But neither of them wanted to die. Therefore, they agreed that each of them comes to the meeting place at a random time between and o'clock in the morning and, after waiting for an opponent minutes, departs. If the other arrives within this interval, the duel will take place. Calculate the probability that the duel will end with a meeting.
Each line is a separate test case and contains an integer (0 < n \le 60).
For each test case, output on a separate line the probability that the duel will end with a meeting. Print the result to decimal places.
Example 1