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)

fn main(){
  let nm: Vec<usize> = read_vec();
  let n = nm[0];
  let m = nm[1];
  let mut q: Vec<(usize, usize)> = Vec::new();
  let mut py: Vec<Vec<usize>> = vec![Vec::new(); n+1];

  for _ in 0..m {
    let tpy: Vec<usize> = read_vec();
    q.push((tpy[0], tpy[1]));
    py[tpy[0]].push(tpy[1]);
  }

  for i in 0..n {
    py[i+1].sort();
  }
  
  for &(p, y) in &q {
    let i: usize = py[p].binary_search(&y).unwrap();
    println!("{:06}{:06}", p, i+1);
  }
}

fn read_vec<T>() -> Vec<T>
  where T: std::str::FromStr,
        T::Err: std::fmt::Debug
{
  let mut buf = String::new();
  std::io::stdin().read_line(&mut buf).expect("failed to read");
  buf.split_whitespace().map(|e| e.parse().unwrap()).collect()
}