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 Lua (5.3.2) (judge verdict: Accepted)

local N, M = io.read("n", "n")
local cities = {}
local prefs = {}
for i=1,M do
     local p, y = io.read("n", "n")
     local c = {i, p, y, -1}
     if not prefs[p] then
         prefs[p] = {}
     end
     table.insert(prefs[p], c)
     table.insert(cities, c)
end
for k, v in pairs(prefs) do
    table.sort(v, function(x1, x2)
        return x1[3] < x2[3]
    end)
    for kk, vv in ipairs(v) do
        local ci = vv[1]
        cities[ci][4] = kk
    end
end

for i=1,M do
    local c = cities[i]
    local p = c[2]
    local x = c[4]
    print(string.format("%06d%06d", p, x))
end