You are given an array integer $A$ of length $n$. Find the number of pairs $(i, j)$ that $A_i = A_j$ and $i \neq j$.
### Input
- The first line contains an integer $n$.
- The second line contains $n$ integers $A_i$.
### Output
- One integer is the number of pairs you found.
### Constraints
- $1 \le n \le 10^5$.
- $1 \le A_i \le 10^5 $.
### Example
Input:
```
5
1 2 2 1 1
```
Output:
```
4
```
