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)

import java.io.PrintWriter
import java.util.*

fun main(args: Array<String>) {
    val out = PrintWriter(System.out)
    val sc = Scanner(System.`in`)
    val n = sc.nextLong()
    val m = sc.nextLong()
    val py = mutableListOf<City113>()
    (0 until m).forEach { i ->
        py.add(City113(i, sc.next().toInt(), sc.next().toLong()))
    }
    out.println(problem113c(n, m, py))
    out.flush()
}

fun problem113c(n: Long, m: Long, py: MutableList<City113>): String {
    var current = 0
    var count = 0
    py.sorted().forEachIndexed { i, city ->
        if (current != city.p) {
            count = 0
            current = city.p
        }
        count++
        var ps = current.toString()
        while (ps.length < 6) {
            ps = "0$ps"
        }
        var cs = count.toString()
        while (cs.length < 6) {
            cs = "0$cs"
        }
        city.ans = ps + cs
    }
    return py.sortedBy { it.city }.joinToString("\n") { it.ans }
}

class City113(val city: Long, val p: Int, val y: Long, var ans: String = "") : Comparable<City113> {
    override fun compareTo(other: City113): Int {
        val diff = this.p - other.p
        if (diff != 0) return diff
        return (this.y - other.y).toInt()
    }
}