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)

#![allow(unused_imports)]
 
use proconio::{input, fastout};
use proconio::marker::*;
use std::collections::HashMap;
 
#[fastout]
fn main() {
  input! {
    n: usize,
    m: usize,
    vals: [(usize, usize);m],
  }
  let mut cities: Vec<Vec<usize>> = vec![vec![];n];
  for (i, year) in vals.iter() {
    cities[i-1].push(*year);
  }

  let mut result: HashMap<usize, usize> = HashMap::new();
  let mut index = 0;
  for i in 0..cities.len() {
    cities[i].sort();
    for (ii, v) in cities[i].iter().enumerate() {
      result.insert(*v, (i+1) * 1_000_000 + ii + 1);
    }
  }
  
  for (_, year) in vals {
    let v = result.get(&year).unwrap();
    println!("{:0>width$}", v.to_string(), width = 12); 
  }  
}