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() {
    fn input<T: std::str::FromStr + Copy> () -> (T, T) {
        let mut ab = String::new();
        std::io::stdin().read_line(&mut ab).unwrap();
        let ab: Vec<T> = ab.trim().split_whitespace().flat_map(str::parse).collect();
        (ab[0], ab[1])
    }

    let (_, m) = input::<usize>();
    let mut ns: Vec<_> = (0..m).map(|i| {
        let (p, y) = input::<usize>();
        (p, y, i)
    }).collect();
    ns.sort();
    let mut cp = 0;
    let mut index = 1;
    let mut ns: Vec<_> = ns.into_iter().map(|(p, _, i)| {
        if p != cp {
            cp = p;
            index = 1;
        } else {
            index += 1;
        }
        (i, format!("{:06}{:06}", cp, index))
    }).collect();
    ns.sort();
    for (_, s) in ns.into_iter() {
        println!("{}", s);
    }
}