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 Haskell (GHC 7.10.3) (judge verdict: Time Limit Exceeded)

import Control.Monad
import Data.Function
import Data.List
import Data.Ord

giveNumber :: [(Int, (Int, Int))] -> [(Int, (Int, Int))]
giveNumber = zipWith (\x (i, (p, y)) -> (i, (p, x))) [1..]

fillDigit6 :: Int -> String
fillDigit6 n = let s = show n in replicate (6 - length s) '0' ++ s

toId :: (Int, Int) -> String
toId (p, x) = fillDigit6 p ++ fillDigit6 x

main = do
    [_, m] <- map read . words <$> getLine
    ds <- replicateM m ((\[x, y] -> (x, y)) . map (read :: String -> Int) . words <$> getLine)
    putStr $ unlines $ map toId $ map snd $ sort $ concat $ map giveNumber $ groupBy ((==) `on` (fst . snd)) $ sortBy (comparing snd) $ zip [1..] ds