Ordinary Number

AtCoder

IDabc132_b

Time2000ms

Memory256MB

Difficulty—

We have a permutation $p$ = {$p_1,\ p_2,\ ...,\ p_n$} of {$1,\ 2,\ ...,\ n$}. Print the number of elements $p_i$ ($1 < i < n$) that satisfy the following condition: * $p_i$ is the second smallest number among the three numbers $p_{i - 1}$, $p_i$, and $p_{i + 1}$. ## Constraints * All values in input are integers. * $3 \leq n \leq 20$ * $p$ is a permutation of {$1,\ 2,\ ...,\ n$}. ## Input Input is given from Standard Input in the following format: $n$ $p_1$ $p_2$ $...$ $p_n$ [samples]

Samples

Input #1

5
1 3 5 4 2

Output #1

2

$p_2 = 3$ is the second smallest number among $p_1 = 1$, $p_2 = 3$, and $p_3 = 5$. Also, $p_4 = 4$ is the second smallest number among $p_3 = 5$, $p_4 = 4$, and $p_5 = 2$. These two elements satisfy the condition.

Input #2

9
9 6 3 2 5 8 7 4 1

Output #2

API Response (JSON)

{
  "problem": {
    "name": "Ordinary Number",
    "description": {
      "content": "We have a permutation $p$ = {$p_1,\\ p_2,\\ ...,\\ p_n$} of {$1,\\ 2,\\ ...,\\ n$}. Print the number of elements $p_i$ ($1 < i < n$) that satisfy the following condition: *   $p_i$ is the second smallest n",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc132_b"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "We have a permutation $p$ = {$p_1,\\ p_2,\\ ...,\\ p_n$} of {$1,\\ 2,\\ ...,\\ n$}.\nPrint the number of elements $p_i$ ($1 < i < n$) that satisfy the following condition:\n\n*   $p_i$ is the second smallest n...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments