Count Good Pairs

You are given an array of integers. Your task is to count the number of good pairs in the array. A pair of indices \( (i, j) \) is called a good pair if:

• \( nums[i] = nums[j] \)
• \( i < j \)

For example, consider the array [1, 2, 3, 1, 1, 3]. There are 4 good pairs: \( (0, 3) \), \( (0, 4) \), \( (3, 4) \), and \( (2, 5) \). Your program should output the total number of such pairs.

inputFormat

The input is given from stdin and consists of two lines:

• The first line contains an integer \( n \), the number of elements in the array.
• The second line contains \( n \) integers separated by spaces.

If \( n = 0 \), then the second line will be empty.

outputFormat

Output to stdout a single integer representing the number of good pairs in the array.

6
1 2 3 1 1 3

4