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(non_snake_case)]
use proconio::input;
// use std::collections::HashMap;
use std::collections::BinaryHeap;

fn main() {
    input! {
        N: usize,
        M: usize,
    }

    let mut Ps = vec![0; M];
    let mut Ys = vec![0; M];
    let mut Xs = vec![0; M];

    for m in 0..M {
        input! {
            P: usize,
            Y: i32,
        }

        Ps[m] = P - 1;
        Ys[m] = Y;
    }

    let mut Heaps = vec![BinaryHeap::new(); N];

    for m in 0..M {
        let P = Ps[m];
        let Y = Ys[m];

        let t = (-Y, m);
        Heaps[P].push(t);
    }

    for n in 0..N {
        let mut x = 0;
        while Heaps[n].peek() != None {
            let t = Heaps[n].pop().unwrap();
            // let Y = - t.0;
            let m = t.1;

            Xs[m] = x;
            x += 1;
        }
    }

    for m in 0..M {
        let P = Ps[m] + 1;
        let x = Xs[m] + 1;
        println!("{:06}{:06}", P, x);
    }
}