Problem7674--[CSES Problem Set] Dice Probability

7674: [CSES Problem Set] Dice Probability

[Creator : ]
Time Limit : 1.000 sec  Memory Limit : 256 MiB

Description

You throw a dice $n$ times, and every throw produces an outcome between $1$ and $6$. 
What is the probability that the sum of outcomes is between $a$ and $b$?

Input

The only input line contains three integers $n, a, b$.

Output

Print the probability rounded to six decimal places.

Constraints

$1≤n≤100$
$1 \le a \le b \le 6n$

Sample 1 Input

2 9 10

Sample 1 Output

0.194444

HINT

相同题目:CSES 1725

Source/Category