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: Runtime Error)

fn c_id() {
    let mut input = String::new();
    std::io::stdin().read_line(&mut input).unwrap();
    let tmp: Vec<usize> = input.trim_right()
        .split_whitespace()
        .map(|s| s.parse::<usize>().unwrap())
        .collect();
    let n = tmp[0];
    let m = tmp[1];

    let mut pref = Vec::new();
    let mut city = Vec::new();
    let mut list : Vec<Vec<usize>> = vec![Vec::new(); n]; 

    for i in 0..m {
        let mut input = String::new();
        std::io::stdin().read_line(&mut input).unwrap();
        let tmp: Vec<usize> = input.trim_right()
            .split_whitespace()
            .map(|s| s.parse::<usize>().unwrap())
            .collect();

        pref.push(tmp[0]);
        city.push(tmp[1]);
        list[tmp[0]].push(tmp[1]);
    }

    for arr in &mut list {
        arr.sort();
    }

    for (p, c) in pref.iter().zip(city.iter()) {
        let index = list[*p].binary_search(c).expect("not found");
        println!("{0: >06}{1: >06}", p, index + 1);
    }
}

fn main() {
    c_id();
}