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 (1.42.0) (judge verdict: Accepted)

use proconio::{input, fastout};

macro_rules! echo {
  ($val:expr) => {
    println!("{}", $val);
  }
}

#[fastout]
fn main() {
  input!{
    n: usize,
    m: usize,
    py: [(usize, usize); m]
  };
  let mut mat : Vec<Vec<(usize, usize)>> = vec![Vec::new(); n+1];

  for (i, (p, y)) in py.iter().enumerate() {
    mat[*p].push((i, *y));
  }

  let mut ans = vec![None; m];

  for i in 0..=n {
    mat[i].sort_by_cached_key(|&t| t.1);
    for (k, (j, _)) in mat[i].iter().enumerate() {
      ans[*j] = Some(format!("{:06}{:06}", i, k+1));
    }
  }
  for a in ans {
    echo!(a.unwrap());
  }
}