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 Python (3.4.3) (judge verdict: Accepted)

def iread():
    return int(input())


def sread():
    return input()


def aread_int():
    tmp = input().split()
    ret = [int(i) for i in tmp]
    return ret


def aread_str():
    return input().split()


def fst(t):
    return t[0]


def snd(t):
    return t[1]


def thd(t):
    return t[2]


if __name__ == '__main__':
    n, m = map(int, input().split())
    l = []
    ans = []
    for i in range(m):
        p, y = map(int, input().split())
        l.append((p, y, i))

    l = sorted(l)
    end = 0
    for i in range(n):
        begin = end
        while end < len(l) and fst(l[end]) == i + 1:
            end += 1
        town = l[begin:end]
        sorted(town, key=lambda x: snd(x))
        tmp = 1
        for e in town:
            ans.append((fst(e), tmp, thd(e)))
            tmp += 1

    ans = sorted(ans, key=lambda x : thd(x))
    for e in ans :
        birth = str(fst(e))
        rate = str(snd(e))
        print(birth.zfill(6) + rate.zfill(6))