Problem:
Score: 300 points

Problem Statement

In Republic of Atcoder, there are N prefectures, and a total of M cities that belong to those prefectures.

City i is established in year Y_i and belongs to Prefecture P_i.

You can assume that there are no multiple cities that are established in the same year.

It is decided to allocate a 12-digit ID number to each city.

If City i is the x-th established city among the cities that belong to Prefecture i, the first six digits of the ID number of City i is P_i, and the last six digits of the ID number is x.

Here, if P_i or x (or both) has less than six digits, zeros are added to the left until it has six digits.

Find the ID numbers for all the cities.

Note that there can be a prefecture with no cities.

Constraints

1 \leq N \leq 10^5

1 \leq M \leq 10^5

1 \leq P_i \leq N

1 \leq Y_i \leq 10^9

Y_i are all different.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N M
P_1 Y_1
:
P_M Y_M

Output

Print the ID numbers for all the cities, in ascending order of indices (City 1, City 2, ...).

Sample Input 1

2 3
1 32
2 63
1 12

Sample Output 1

000001000002
000002000001
000001000001

As City 1 is the second established city among the cities that belong to Prefecture 1, its ID number is 000001000002.

As City 2 is the first established city among the cities that belong to Prefecture 2, its ID number is 000002000001.

As City 3 is the first established city among the cities that belong to Prefecture 1, its ID number is 000001000001.

Sample Input 2

2 3
2 55
2 77
2 99

Sample Output 2

000002000001
000002000002
000002000003

Solution in Kotlin (1.0.0) (judge verdict: Accepted)

fun main(args: Array<String>) {
    // 全体一括ソートは遅いはずだが，StringBuilder を使っている部分で実行速度が上がっている？？

    val (n, m) = readLine()!!.split(" ").map { it.toInt() }

    // 各県の初期ランクを定義
    var rank = IntArray(n + 1) { 1 }


    // 全ての市を year で一括並び替え
    val cities=(1..m).map {
        // map の中で複数の式を定義している
        val (p, y) = readLine()!!.split(" ").map { it.toInt() }

        // map の lambda式でのローカルリターンを定義（@map が付いていないと main でのリターンになってしまう)
        // Kotlinのラムダでreturnする : https://qiita.com/MasanoriMT/items/f5e814737479ff8d6fec
        // return が明示的に書かれているとわかりやすいが， return を書かなくても最後の式の評価結果が戻り値となる
        return@map Triple(it, p, y)
    }.sortedBy { it.third }

//    val sb=StringBuilder()
//
//    // 各市に県内で何番目かの情報を付与した後に，入力順にソート
//    cities.map {
//        // 同じ県内で何番目かの情報付与
//        Pair(it,rank[it.second]++)
//    }.sortedBy {
//        // データの入力順にソート
//        it.first.first
//    }.forEach {
//        // 出力文字列を StringBuilder に格納
//        sb.append(it.first.second.toString().padStart(6,'0'))
//        sb.append(it.second.toString().padStart(6,'0'))
//        sb.append("\n")
//    }
//
//    // まとめて出力
//    println(sb)

    // 仮にStringBuilder を使わなかった場合

    // 各市に県内で何番目かの情報を付与した後に，入力順にソート
    val ans = cities.map {
        // 同じ県内で何番目かの情報付与
        Pair(it,rank[it.second]++)
    }.sortedBy {
        // データの入力順にソート
        it.first.first
    }.map {
        // 出力文字列を StringBuilder に格納
        it.first.second.toString().padStart(6,'0') + it.second.toString().padStart(6,'0')
    }

    println(ans.joinToString("\n"))
}