#abc206c. [abc206_c]Swappable
[abc206_c]Swappable
Problem Statement
Given an array of integers , find the number of pairs of integers satisfying all of the following conditions:
Constraints
- All values in input are integers.
Input
Input is given from Standard Input in the following format:
Output
Print the answer as an integer.
Sample Input 1
Sample Output 1
In this input, we have .
- For the pair , .
- For the pair , .
- For the pair , .