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**Task** | Statistics

Time limit: | 1.00 s | Memory limit: | 512 MB |

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 $b$?

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

Print the probability rounded to six decimal places.

- $1 \le n \le 100$

- $1 \le a \le b \le 6n$

Input:

`2 9 10`

Output:

`0.194444`