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: Accepted)

import qualified Data.ByteString.Char8 as BC
import Data.Maybe
import qualified Data.IntMap as IM
import Data.List

type Map = IM.IntMap Int

readIntsLines :: IO [[Int]]
readIntsLines = map (map (fst . fromJust . BC.readInt) . BC.words) . BC.lines <$> BC.getContents

get :: Int -> Map -> Int
get key m = fromMaybe 1 $ IM.lookup key m

set :: Int -> Int -> Map -> Map
set = IM.insert

solve :: [(Int, Int, Int)] -> Map -> [(Int, String)]
solve [] _ = []
solve ((i, p, y):pys) m = (i, result) : solve pys next
  where curr = get p m
        sp = show p
        sc = show curr
        result = replicate (6 - length sp) '0' ++ sp ++ replicate (6 - length sc) '0' ++ sc
        next = set p (curr + 1) m

main :: IO ()
main = do
  getLine
  pys <- readIntsLines
  let z i l = (i, head l, last l)
  let year (_, _, y) = y
  let ds = sortOn year $ zipWith z [1..] pys
  let result = map snd . sortOn fst $ solve ds IM.empty
  mapM_ putStrLn result