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: Wrong Answer)

import Control.Monad
import Data.List
import qualified Data.ByteString.Char8 as B
import qualified Data.IntMap as M

main = do
    (n:m:_)<-map read.words<$>getLine::IO[Int]
    pys<-replicateM m $ unfoldr (B.readInt.B.dropWhile(==' '))<$>B.getLine::IO[[Int]]

    let mp = foldl' (\m ((p:y:_),n)->M.alter (f (y,n)) p m) M.empty $ zip pys [1..]
    --
    let ns = sort $ concatMap (\(p, m)-> (map (\((_,c),n)->(c, (p,n)) ) $ zip (M.toAscList m) [1..])) $ M.toAscList mp
    putStr $ unlines $ map g ns
--
f (y,n) Nothing = Just (M.singleton y n)
f (y,n) (Just m) = Just (M.insert y n m)
--
g (_,(p,x)) = drop (length $ show p) ("000000"++show p) ++ drop (length $ show p) ("000000"++show x)