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: Wrong Answer)

import numpy as np

N,M = map(int,input().split(" "))

p_ls = []
y_ls = []
for _ in range(M):
    p,y = map(int,input().split(" "))
    p_ls.append(p)
    y_ls.append(y)

p_ar = np.array(p_ls)
y_ar = np.array(y_ls)


# 市ごとに連続するようにする
p_ind = p_ar.argsort()
p_sorted = p_ar[p_ind]
y_sorted = y_ar[p_ind]
x_ar_sorted = np.zeros(len(p_ls))


ind = 0

while ind < M:
    d = 0
    while ind+d < M-1 and p_sorted[ind] == p_sorted[ind+d+1]:
        d+=1
    tmp_x = y_sorted[ind:ind+d+1].argsort()+1
    x_ar_sorted[ind:ind+d+1] = tmp_x
    ind = ind + d + 1

for i in range(M):
    print('%06d'%p_ar[i] + '%06d'%x_ar_sorted[p_ind[i]])