#5709. CSES2417 计数互质数对
0
CSES2417 计数互质数对
Counting Coprime Pairs
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
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.
Output
Print one integer: the answer for the task.
Constraints
Example
Input
8
5 4 20 1 16 17 5 15
Output
19