Given an array of ~ n ~ positive integers ~ a_1, a_2, a_3, \ldots, a_{n-1}, a_n ~.

Requirement: Determine how many pairs of equal numbers there are (~ a_i = a_j ~ with ~ i < j ~).

Input

• The first line contains the length ~ n ~ of the array (~ 1 \leq n \leq 10^5 ~).
• The second line contains ~ n ~ integers ~ a_1, a_2, a_3, \ldots, a_n ~ (~ 1 \leq a_i \leq 10^6 ~), separated by spaces.

Output

• An integer representing the number of equal pairs.

Sample Input

7
6 2 4 2 4 3 4

Sample Output

4