Sum of fractions

Write a program that reads triples of natural numbers $a$ , $b$ and $k$ , and for each one computes and prints the result of $\frac{1}{a} + \frac{1}{a+k} + \frac{1}{a+2k} + \dots$ for all fractions with denominator smaller than or equal to $b$ .

Input

Input consists of several triples of natural numbers $a$ , $b$ and $k$ , such that $1 \le a\le b$ and $k \ge 1$ .

Output

For each triple, print in a line the result of the sum with four digits after the decimal point.

Problem information

Author: Unknown
Translator: Carlos Molina

Generation: 2026-01-25T11:52:16.876Z