Non-decreasing

AtCoder

IDarc086_b

Time2000ms

Memory256MB

Difficulty—

Snuke has an integer sequence, $a$, of length $N$. The $i$\-th element of $a$ ($1$\-indexed) is $a_{i}$. He can perform the following operation any number of times: * Operation: Choose integers $x$ and $y$ between $1$ and $N$ (inclusive), and add $a_x$ to $a_y$. He would like to perform this operation between $0$ and $2N$ times (inclusive) so that $a$ satisfies the condition below. Show one such sequence of operations. It can be proved that such a sequence of operations always exists under the constraints in this problem. * Condition: $a_1 \leq a_2 \leq ... \leq a_{N}$ ## Constraints * $2 \leq N \leq 50$ * $-10^{6} \leq a_i \leq 10^{6}$ * All input values are integers. ## Input Input is given from Standard Input in the following format: $N$ $a_1$ $a_2$ $...$ $a_{N}$ [samples]

Samples

Input #1

3
-2 5 -1

Output #1

2
2 3
3 3

*   After the first operation, $a = (-2,5,4)$.
*   After the second operation, $a = (-2,5,8)$, and the condition is now satisfied.

Input #2

2
-1 -3

Output #2

1
2 1

*   After the first operation, $a = (-4,-3)$ and the condition is now satisfied.

Input #3

5
0 0 0 0 0

Output #3

0

*   The condition is satisfied already in the beginning.

API Response (JSON)

{
  "problem": {
    "name": "Non-decreasing",
    "description": {
      "content": "Snuke has an integer sequence, $a$, of length $N$. The $i$\\-th element of $a$ ($1$\\-indexed) is $a_{i}$. He can perform the following operation any number of times: *   Operation: Choose integers $x$",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "arc086_b"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "Snuke has an integer sequence, $a$, of length $N$. The $i$\\-th element of $a$ ($1$\\-indexed) is $a_{i}$.\nHe can perform the following operation any number of times:\n\n*   Operation: Choose integers $x$...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments