Passing Score Percentage

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

Given n integer scores from 0 to 10, a score of at least 5 passes. Print the percentage of passing students with exactly two decimal digits and without a percent sign.

Input

Integer n, then exactly n scores separated by whitespace.

Output

One percentage number with exactly two decimals (%.2f) and a newline.

Subtasks

• Subtask 1 (20%): 1 ≤ n ≤ 10, scores 0..10.

• Subtask 2 (30%): 1 ≤ n ≤ 1000, scores 0..10.

• Subtask 3 (50%): 1 ≤ n ≤ 10000, scores 0..10.

Examples

Example 1

Input:

4
4 5 6 0

Output:

50.00

Explanation: Two of four students pass, giving 50.00 percent.

Example 2

Input:

3
0 1 4

Output:

0.00

Explanation: All scores are below 5, so the percentage is 0.00.