Reversible Cards

AtCoder

IDarc111_b

Time2000ms

Memory256MB

Difficulty—

We have $N$ cards numbered $1$ to $N$. Each side of each card has a color represented by a positive integer. One side of Card $i$ has a color $a_i$, and the other side has a color $b_i$. For each card, you can choose which side shows up. Find the maximum possible number of different colors showing up. ## Constraints * $1 \leq N \leq 200000$ * $1 \leq a_i,b_i \leq 400000$ * All numbers in input are integers. ## Input Input is given from Standard Input in the following format: $N$ $a_1$ $b_1$ $a_2$ $b_2$ $:$ $a_N$ $b_N$ [samples]

Samples

Input #1

Output #1

4

We can choose the sides with $1$, $3$, $4$, $2$ to have four colors.

Input #2

2
111 111
111 111

Output #2

1

They are painted with just one color.

Input #3

Output #3

API Response (JSON)

{
  "problem": {
    "name": "Reversible Cards",
    "description": {
      "content": "We have $N$ cards numbered $1$ to $N$. Each side of each card has a color represented by a positive integer. One side of Card $i$ has a color $a_i$, and the other side has a color $b_i$. For each card",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "arc111_b"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "We have $N$ cards numbered $1$ to $N$. Each side of each card has a color represented by a positive integer.\nOne side of Card $i$ has a color $a_i$, and the other side has a color $b_i$.\nFor each card...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments