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 B
import qualified Data.Map as MP
import qualified Data.Vector.Unboxed as VU
import Data.Char
import Data.List

toTuple :: B.ByteString -> (Int, Int)
toTuple bs =
    let
        Just (a, bs') = B.readInt bs
        Just (b, _) = B.readInt $ B.dropWhile isSpace bs'
    in
        (a, b)

make :: MP.Map Int [Int] -> (Int, Int) -> MP.Map Int [Int]
make m (a,b) =
    case MP.lookup a m of
        Just _ -> MP.adjust (b:) a m
        Nothing -> MP.insert a [b] m

rebuild :: MP.Map Int [Int] -> MP.Map Int (VU.Vector Int) -> MP.Map Int (VU.Vector Int)
rebuild m n
    | MP.null m = n
    | otherwise = rebuild m' (MP.insert i xs' n)
        where
            ((i,xs),m') = MP.deleteFindMin m
            xs' = VU.fromList $ sort xs

lowerBound :: VU.Vector Int -> (Int, Int) -> Int -> Int
lowerBound vec (from, to) target
    | from == to = from
    | mValue >= target = lowerBound vec (from, mid) target
    | mValue < target = lowerBound vec (mid + 1, to) target
        where
            mid = (from + to) `quot` 2
            mValue = vec VU.! mid

comp :: Int -> String
comp n = zero ++ n'
    where
        n' = show n
        zero = replicate (6 - (length n')) '0'

main = do
    [n,m] <- map read . words <$> getLine
    xs <- VU.replicateM m (toTuple <$> B.getLine)
    let m = VU.foldl' make MP.empty xs
    let m' = rebuild m MP.empty
    VU.forM_ xs $ \(p,y) -> do
        let Just ys = MP.lookup p m'
        let lb = lowerBound ys (0, VU.length ys) y
        putStrLn $ comp p ++ comp (lb+1)