#AT1119. C - Make a Rectangle
C - Make a Rectangle
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C - Make a Rectangle
Score : $300$ points
Problem Statement
We have $N$ sticks with negligible thickness. The length of the $i$-th stick is $A_i$.
Snuke wants to select four different sticks from these sticks and form a rectangle (including a square), using the sticks as its sides. Find the maximum possible area of the rectangle.
Constraints
- $4 \leq N \leq 10^5$
- $1 \leq A_i \leq 10^9$
- $A_i$ is an integer.
Input
Input is given from Standard Input in the following format:
...
Output
Print the maximum possible area of the rectangle. If no rectangle can be formed, print $0$.
6
3 1 2 4 2 1
2
$1 \times 2$ rectangle can be formed.
4
1 2 3 4
0
No rectangle can be formed.
10
3 3 3 3 4 4 4 5 5 5
20