Make a Rectangle

AtCoder

IDarc081_a

Time2000ms

Memory256MB

Difficulty—

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: $N$ $A_1$ $A_2$ ... $A_N$ [samples]

Samples

Input #1

6
3 1 2 4 2 1

Output #1

2

$1 \times 2$ rectangle can be formed.

Input #2

4
1 2 3 4

Output #2

0

No rectangle can be formed.

Input #3

10
3 3 3 3 4 4 4 5 5 5

Output #3

API Response (JSON)

{
  "problem": {
    "name": "Make a Rectangle",
    "description": {
      "content": "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 t",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "arc081_a"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "We have $N$ sticks with negligible thickness. The length of the $i$\\-th stick is $A_i$.\nSnuke wants to select four different sticks from these sticks and form a rectangle (including a square), using t...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments