The Pilots Brothers' refrigerator

Luogu

IDLGP10456

Time1000ms

Memory512MB

DifficultyP4

2004Special JudgeICPC

The game “The Pilots Brothers: following the stripy elephant” has a quest where a player needs to open a refrigerator. There are $16$ handles on the refrigerator door. Every handle can be in one of two states: open or closed. The refrigerator is open only when all handles are open. The handles are represented as a matrix $4\times4$. You can change the state of a handle in any location $[i, j] (1 \leq i, j \leq 4)$. However, this also changes states of all handles in row $i$ and all handles in column $j$. The task is to determine the minimum number of handle switching necessary to open the refrigerator. ## Input The input contains four lines. Each of the four lines contains four characters describing the initial state of appropriate handles. A symbol “+” means that the handle is in closed state, whereas the symbol “−” means “open”. At least one of the handles is initially closed. ## Output The first line of the input contains $N$ – the minimum number of switching. The rest $N$ lines describe switching sequence. Each of the lines contains a row number and a column number of the matrix separated by one or more spaces. If there are several solutions, you may give any one of them. [samples]

Samples

Input #1

-+--
----
----
-+--

Output #1

API Response (JSON)

{
  "problem": {
    "name": "The Pilots Brothers' refrigerator",
    "description": {
      "content": "The game “The Pilots Brothers: following the stripy elephant” has a quest where a player needs to open a refrigerator. There are $16$ handles on the refrigerator door. Every handle can be in one of t",
      "description_type": "Markdown"
    },
    "platform": "Luogu",
    "limit": {
      "time_limit": 1000,
      "memory_limit": 524288
    },
    "difficulty": {
      "LuoguStyle": "P4"
    },
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "LGP10456"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "The game “The Pilots Brothers: following the stripy elephant” has a quest where a player needs to open a refrigerator.\n\nThere are $16$ handles on the refrigerator door. Every handle can be in one of t...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments