Dice Probability

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 and b. Output Print the probability rounded to six decimal places (rounding half to even). Constraints - 1 \le n \le 100 - 1 \le a \le b \le 6n Example Input: 2 9 10 Output: 0.194444