Golden Apple

AtCoder

IDabc134_b

Time2000ms

Memory256MB

Difficulty—

There are $N$ apple trees in a row. People say that one of them will bear golden apples. We want to deploy some number of inspectors so that each of these trees will be inspected. Each inspector will be deployed under one of the trees. For convenience, we will assign numbers from $1$ through $N$ to the trees. An inspector deployed under the $i$\-th tree $(1 \leq i \leq N)$ will inspect the trees with numbers between $i-D$ and $i+D$ (inclusive). Find the minimum number of inspectors that we need to deploy to achieve the objective. ## Constraints * All values in input are integers. * $1 \leq N \leq 20$ * $1 \leq D \leq 20$ ## Input Input is given from Standard Input in the following format: $N$ $D$ [samples]

Samples

Input #1

6 2

Output #1

2

We can achieve the objective by, for example, placing an inspector under Tree $3$ and Tree $4$.

Input #2

14 3

Output #2

Input #3

20 4

Output #3

API Response (JSON)

{
  "problem": {
    "name": "Golden Apple",
    "description": {
      "content": "There are $N$ apple trees in a row. People say that one of them will bear golden apples. We want to deploy some number of inspectors so that each of these trees will be inspected. Each inspector will ",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc134_b"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "There are $N$ apple trees in a row. People say that one of them will bear golden apples.\nWe want to deploy some number of inspectors so that each of these trees will be inspected.\nEach inspector will ...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments