6843.Counting Coprime Pairs

Time Limit: 1s Memory Limit: 512MB

Given a list of $n$ positive integers, your task is to count the number of pairs of integers that are coprime (i.e., their greatest common divisor is one).

Input Format(From the terminal/stdin)

The first input line has an integer $n$ : the number of elements.

The next line has $n$ integers $x_1,x_2,\dots,x_n$ : the contents of the list.

  • $1 \le n \le 10^5$
  • $1 \le x_i \le 10^6$

Output Format(To the terminal/stdout)

Print one integer: the answer for the task.

Sample Input

Copy
8
5 4 20 1 16 17 5 15
 \n
 · ·  · ·  ·  · ·  \n

Sample Output

Copy
19
  \n
Source: CSES, Mathematics, 2417

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