9396: ABC206 —— C - Swappable
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Description
Given an array of $N$ integers $A=(A_1,A_2,...,A_N)$, find the number of pairs $(i,j)$ of integers satisfying all of the following conditions:
- $1 \le i < j \le N$
- $A_i \neq A_j$
- $1 \le i < j \le N$
- $A_i \neq A_j$
Input
Input is given from Standard Input in the following format:
```
$N$
$A_1$ $A_2$ $\dots$ $A_N$
```
```
$N$
$A_1$ $A_2$ $\dots$ $A_N$
```
Output
Print the answer as an integer.
Constraints
- All values in input are integers.
- $2 \le N \le 3 \times 10^5$
- $1 \le A_i \le 10^9$
- $2 \le N \le 3 \times 10^5$
- $1 \le A_i \le 10^9$
Sample 1 Input
3
1 7 1
Sample 1 Output
2
In this input, we have A=(1,7,1).
- For the pair (1,2), $A_1\neq A_2$.
- For the pair (1,3), $A_1=A_3$.
- For the pair (2,3), $A_2\neq A_3$.
Sample 2 Input
10
1 10 100 1000 10000 100000 1000000 10000000 100000000 1000000000
Sample 2 Output
45
Sample 3 Input
20
7 8 1 1 4 9 9 6 8 2 4 1 1 9 5 5 5 3 6 4
Sample 3 Output
173