Score: 300 points
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.
Input is given from Standard Input in the following format:
N M P_1 Y_1 : P_M Y_M
Print the ID numbers for all the cities, in ascending order of indices (City 1, City 2, ...).
2 3 1 32 2 63 1 12
000001000002 000002000001 000001000001
2 3 2 55 2 77 2 99
000002000001 000002000002 000002000003