Harmonic numbers (2) P58153

Statement

Write a program that reads pairs of numbers $n$ and $m$ with $n \ge m$ , and for each pair prints $H_n - H_m$ .

Input

Input consists of several pairs of natural numbers $n$ and $m$ such that $n \ge m$ .

For every pair, print $H_n - H_m$ with 10 digits after the decimal point.

Public test cases

Input

Output

0.3333333333
2.5928571429
0.0000000000
0.0100000000

Information