Right Triangle

AtCoder

IDabc116_a

Time2000ms

Memory256MB

Difficulty—

There is a right triangle $ABC$ with $∠ABC=90°$. Given the lengths of the three sides, $|AB|,|BC|$ and $|CA|$, find the area of the right triangle $ABC$. It is guaranteed that the area of the triangle $ABC$ is an integer. ## Constraints * $1 \leq |AB|,|BC|,|CA| \leq 100$ * All values in input are integers. * The area of the triangle $ABC$ is an integer. ## Input Input is given from Standard Input in the following format: $|AB|$ $|BC|$ $|CA|$ [samples]

Samples

Input #1

3 4 5

Output #1

6

![image](https://img.atcoder.jp/ghi/44c1d4cbdf4677ce3b08ca70b5ce98ea.png)
This triangle has an area of $6$.

Input #2

5 12 13

Output #2

30

This triangle has an area of $30$.

Input #3

45 28 53

Output #3

630

This triangle has an area of $630$.

API Response (JSON)

{
  "problem": {
    "name": "Right Triangle",
    "description": {
      "content": "There is a right triangle $ABC$ with $∠ABC=90°$. Given the lengths of the three sides, $|AB|,|BC|$ and $|CA|$, find the area of the right triangle $ABC$. It is guaranteed that the area of the triangle",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc116_a"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "There is a right triangle $ABC$ with $∠ABC=90°$.\nGiven the lengths of the three sides, $|AB|,|BC|$ and $|CA|$, find the area of the right triangle $ABC$.\nIt is guaranteed that the area of the triangle...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

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