S Sequence II

Source: beecrowd

Version: Phuoc Hung OJ Extended

Problem Statement

Calculate $S=1+\frac32+\frac54+\frac78+\cdots+\frac{39}{2^{19}}$. Numerators increase by 2 from 1 to 39 and denominators double from 1. Print the value rounded to exactly two decimal places.

Input

There is no input.

Output

Print one line with exactly two decimal places.

Subtasks

• Subtask 1 (20%): No input; the same empty input is used for scoring groups.

• Subtask 2 (30%): No input; the same empty input is used for scoring groups.

• Subtask 3 (50%): No input; the same empty input is used for scoring groups.

Examples

Example 1

Input:

Output:

6.00

Explanation:

Sum 20 fractions with odd numerators 1 through 39 and denominators doubling from 1; print two decimals.