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)

use std::cmp::Ordering;

fn read<T: std::str::FromStr>(
    stdin_lock: &mut std::io::StdinLock,
    buf: &mut Vec<u8>,
    delimiter: u8,
) -> T {
    buf.clear();
    let l = std::io::BufRead::read_until(stdin_lock, delimiter, buf).unwrap();
    buf.truncate(l - 1); // remove delimiter
    let s = unsafe { std::str::from_utf8_unchecked(&buf) };
    s.parse().unwrap_or_else(|_| panic!("read"))
}

fn main() {
    let stdin = std::io::stdin();
    let mut stdin_lock = stdin.lock();
    let mut buf: Vec<u8> = Vec::new();
    let _: usize = read(&mut stdin_lock, &mut buf, b' ');
    let m: usize = read(&mut stdin_lock, &mut buf, b'\n');
    let mut cv = vec![(0i32, 0i32, 0i32, 0i32); m];
    for i in 0..m {
        cv[i].0 = i as i32;
        cv[i].1 = read(&mut stdin_lock, &mut buf, b' ');
        cv[i].2 = read(&mut stdin_lock, &mut buf, b'\n');
    }

    cv.sort_by(|&(_, p1, y1, _), &(_, p2, y2, _)| match p1.cmp(&p2) {
        Ordering::Less => Ordering::Less,
        Ordering::Greater => Ordering::Greater,
        Ordering::Equal => y1.cmp(&y2),
    });
    let mut j = 1;
    cv[0].3 = 1;
    for i in 1..m {
        j = if cv[i - 1].1 == cv[i].1 { j + 1 } else { 1 };
        cv[i].3 = j;
    }
    cv.sort_by(|&(i1, _, _, _), &(i2, _, _, _)| i1.cmp(&i2));

    for i in 0..m {
        println!("{:06}{:06}", cv[i].1, cv[i].3);
    }
}