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)

{-# LANGUAGE BangPatterns, MultiWayIf #-}

import Control.Applicative
import Control.Monad
import Data.List
import Debug.Trace (traceShow, traceShowM)

import Text.Printf (printf)
import Control.Monad.ST
import Data.Array.ST
import Data.Array
import qualified Data.IntMap.Strict as M

f1 xs = [(j, k, i) | (i, (j, k)) <- zip [1..] xs]

solve :: Int -> Int -> [(Int, Int)] -> IO ()
solve n m pys = forM_ pys $ \(i, j) -> do
    let m = ary ! i
    let a = m M.! j
    printf "%06d%06d\n" i (a :: Int)
  where
    ps = groupBy (\a b -> fst a == fst b) $ sort pys
    ary = runSTArray $ do
        a <- newArray (1, n) M.empty
        let qs = fmap f1 ps
        forM_ qs $ \gs -> do
            forM_ gs $ \(i, j, k) -> do
                m <- readArray a i
                writeArray a i (M.insert j k m)
        return a

main :: IO ()
main = do
    [n, m] <- fmap read . words <$> getLine :: IO [Int]
    pys <- replicateM m $ do
        [p, y] <- fmap read . words <$> getLine
        return (p, y) :: IO (Int, Int)
    solve n m pys