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)

use std::cmp;

#[allow(dead_code)]
fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

#[allow(dead_code)]
fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

#[allow(dead_code)]
fn read_vec2<T: std::str::FromStr>(n: u32) -> Vec<Vec<T>> {
    (0..n).map(|_| read_vec()).collect()
}

#[allow(dead_code)]
fn find_min(x: &[u64]) -> u64 {
    let mut min: u64 = x[0];
    let mut x_iter = x.iter();
    while let Some(i) = x_iter.next() {
        min = cmp::min(*i, min);
    }
    return min;
}

#[allow(dead_code)]
fn find_max(x: &[u64]) -> u64 {
    let mut max: u64 = x[0];
    let mut x_iter = x.iter();
    while let Some(i) = x_iter.next() {
        max = cmp::max(*i, max);
    }
    return max;
}
fn main() {
    let init: Vec<usize> = read_vec();
    let n = init[0];
    let m = init[1];

    let year: Vec<Vec<u32>> = read_vec2(m as u32);

    let mut calc: Vec<Vec<u32>> = Vec::new();
    for _i in 0..m {
        let tmp: Vec<u32> = vec![0];
        calc.push(tmp);
    }

    for i in 0..m {
        calc[year[i][0] as usize - 1].push(year[i][1]);
    }
    for i in 0..n {
        calc[i].sort();
    }
    for i in 0..m {
        let position: usize = calc[year[i][0] as usize - 1]
            .iter()
            .position(|&x| x == year[i][1])
            .unwrap();
        println!("{:>06}{:>06}", year[i][0], position);
    }
}