题目描述
Background
"…Any Pepsi drink purchased before June 2002 will have a Pepsi star's name on the bottle cap. By collecting all the names of Pepsi stars, you can enter the draw for the Pepsi World Cup Journey, winning a球星 backpack, a portable music player, and even a trip to Japan and South Korea to watch the World Cup. Don't hesitate, act now!"
Problem Description
You turn off the TV and think: Suppose there are \( n \) different star names, each with an equal probability of appearing. On average, how many bottles of drinks do you need to buy to collect all the names?
Input Format
The input consists of a single integer on one line, representing the number of different star names \( n \).
Output Format
Output the average number of bottles needed to collect all the names. If it is an integer, output it directly. Otherwise, output it in fractional format. For example, three and three twentieths should be output as:
3
5--
20
The first line is the numerator of the fractional part, the second line starts with the integer part followed by a line made of minus signs, and the third line is the denominator. The number of minus signs should be equal to the number of digits in the denominator. The first digit of the numerator and the denominator should be aligned with the first minus sign.
The fraction must be irreducible.
Sample Input and Output
Sample Input #1
2
Sample Output #1
3
Sample Input #2
17
Sample Output #2
340463
58------
720720
Notes
Data Range and Constraints
For all test cases, it is guaranteed that \( 2 \leq n \leq 33 \).
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分