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 PyPy3 (7.3.0) (judge verdict: Accepted)

def main():
    N, M = (int(i) for i in input().split())
    PY = [([int(i) for i in input().split()], j) for j in range(M)]
    dic = {i: [] for i in range(N)}  # 県iの市を生まれた順に持つ
    A = sorted(PY, key=lambda p: p[0][1])
    for py, i in A:
        dic[py[0]-1].append(i)

    ans = []
    for p in range(N):  # 県ごとに番号を振る
        for x, i in enumerate(dic[p], start=1):
            # 県pの中でx番目に生まれた市i
            upper = "{:>06}".format(str(PY[i][0][0]))
            lower = "{:>06}".format(str(x))
            ans.append((upper+lower, i))
    ans.sort(key=lambda p: p[1])
    for a, _ in ans:
        print(a)


if __name__ == '__main__':
    main()