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 (1.3.71) (judge verdict: Accepted)

fun intList() = readLine()?.split(" ")?.map(String::toInt) ?: TODO()
fun longList() = readLine()?.split(" ")?.map(String::toLong) ?: TODO()
fun main(args: Array<String>) {
    val (n, m) = intList()
    val array1 = Array<MutableList<Long>>(n + 1) { mutableListOf() }
    val array2 = Array<HashMap<Long, Int>>(n + 1) { hashMapOf() }
    val ps = mutableListOf<Pair<Long, Long>>()
    repeat(m) {
        val (p, y) = longList()
        array1[p.toInt()].add(y)
        ps.add(Pair(p, y))
    }
    repeat(n + 1) { i ->
        array1[i].sort()
        array1[i].forEachIndexed { j, y ->
            array2[i][y] = j
        }
    }
    buildString {
        ps.forEach {
            appendln("%06d%06d".format(it.first, array2[it.first.toInt()][it.second]!! + 1))
        }
    }.let {
        println(it.trimIndent())
    }
}