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 Rust (1.15.1) (judge verdict: Accepted)

#![allow(unused_variables)]
#![allow(unused_imports)]
#![allow(dead_code)]
use std::io;
use std::str::FromStr;
use std::iter::FromIterator;
use std::cmp::{max, min, Ordering};
use std::collections::*;
use std::mem::{replace, swap};

// [NOTE] つかうときには trim() 入れないと RE になるので注意
// abcde
fn read_as_line() -> String {
    let mut line = String::new();
    io::stdin().read_line(&mut line).unwrap();
    line
}

// -3.2
fn read_as_primitive<T: FromStr>() -> T {
    let s = read_as_line();
    s.trim().parse().ok().expect("failed to parse input")
}

// 1 -3 0 999
fn read_as_collection<U: FromStr, T: FromIterator<U>>() -> T {
    let s = read_as_line();
    s.trim().split_whitespace().map(|s| s.parse().ok().expect("failed to parse")).collect()
}

// #.#.###..
fn read_as_chars<T: FromIterator<char>>() -> T {
    let s = read_as_line();
    s.trim().chars().collect()
}

// 1 abc
fn read_as_pair<T: FromStr, U: FromStr>() -> (T, U) {
    let s = read_as_line();
    let mut it = s.trim().split_whitespace();
    (
        it.next().unwrap().parse().ok().expect("failed to parse"),
        it.next().unwrap().parse().ok().expect("failed to parse"),
    )
}

// 1.5 -2 abc
fn read_as_triple<T: FromStr, U: FromStr, V: FromStr>() -> (T, U, V) {
    let s = read_as_line();
    let mut it = s.trim().split_whitespace();
    (
        it.next().unwrap().parse().ok().expect("failed to parse"),
        it.next().unwrap().parse().ok().expect("failed to parse"),
        it.next().unwrap().parse().ok().expect("failed to parse"),
    )
}

fn main() {
    let (n, m): (usize, usize) = read_as_pair();
    let mut bag = HashMap::new();

    for i in 0..m {
        let (p, y): (usize, usize) = read_as_pair();
        bag.entry(p).or_insert(vec![]).push((y, p, i));
    }

    let mut ans = vec![String::from(""); m];
    for p in 1..n+1 {
        if bag.contains_key(&p) {
            let mut xs = bag.get_mut(&p).unwrap();
            xs.sort();
            let it = xs.iter().map(|&(y, p, i)| (p, i)).enumerate();
            for (k, (p, i)) in it {
                ans[i] = format!("{:06}{:06}", p, k + 1);
            }
        }   
    }
    for i in 0..m {
        println!("{}", ans[i]);
    }

}