#![allow(unused_mut, non_snake_case,unused_imports)]
use std::iter;
use std::cmp::{max, min, Ordering};
use std::mem::{swap};
use std::collections::{HashMap,BTreeMap,HashSet,BTreeSet,BinaryHeap,VecDeque};
use std::iter::FromIterator;

//　高速 EOF要
//macro_rules! input {(source = $s:expr, $($r:tt)*) => {let mut iter = $s.split_whitespace();input_inner!{iter, $($r)*}};($($r:tt)*) => {let mut s = {use std::io::Read;let mut s = String::new();std::io::stdin().read_to_string(&mut s).unwrap();s};let mut iter = s.split_whitespace();input_inner!{iter, $($r)*}};}
//macro_rules! input_inner {($iter:expr) => {};($iter:expr, ) => {};($iter:expr, $var:ident : $t:tt $($r:tt)*) => {let $var = read_value!($iter, $t);input_inner!{$iter $($r)*}};}
//macro_rules! read_value {($iter:expr, ( $($t:tt),* )) => {( $(read_value!($iter, $t)),* )};($iter:expr, [ $t:tt ; $len:expr ]) => {(0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()};($iter:expr, chars) => {read_value!($iter, String).chars().collect::<Vec<char>>()};($iter:expr, usize1) => {read_value!($iter, usize) - 1};($iter:expr, $t:ty) => {$iter.next().unwrap().parse::<$t>().expect("Parse error")};}
// 低速 EOF不要
macro_rules! input {(source = $s:expr, $($r:tt)*) => {let mut iter = $s.split_whitespace();let mut next = || { iter.next().unwrap() };input_inner!{next, $($r)*}};($($r:tt)*) => {let stdin = std::io::stdin();let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));let mut next = move || -> String{bytes.by_ref().map(|r|r.unwrap() as char).skip_while(|c|c.is_whitespace()).take_while(|c|!c.is_whitespace()).collect()};input_inner!{next, $($r)*}};}
macro_rules! input_inner {($next:expr) => {};($next:expr, ) => {};($next:expr, $var:ident : $t:tt $($r:tt)*) => {let $var = read_value!($next, $t);input_inner!{$next $($r)*}};}
macro_rules! read_value {($next:expr, ( $($t:tt),* )) => {( $(read_value!($next, $t)),* )};($next:expr, [ $t:tt ; $len:expr ]) => {(0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()};($next:expr, chars) => {read_value!($next, String).chars().collect::<Vec<char>>()};($next:expr, usize1) => {read_value!($next, usize) - 1};($next:expr, $t:ty) => {$next().parse::<$t>().expect("Parse error")};}

// 非常時
fn read_line() -> String{ let mut s = String::new(); std::io::stdin().read_line(&mut s).unwrap(); s.trim().to_string() }

/*
 <url:>
 問題文============================================================
 =================================================================
 解説=============================================================
 ================================================================
 */
fn main(){
    input!(N:i64,M:i64,info:[(i64,i64);M]);
    let mut info_with_idx = Vec::<(i64,i64,i64)>::new();
    for i in 0..M as usize{
        info_with_idx.push((info[i].0,info[i].1,i as i64));
    }
    info_with_idx.sort();

    let mut city_cnt = vec![1;N as usize+1];
    let mut ans = Vec::<(String,i64)>::new();
    for i in 0..M as usize{
        let (city,_,idx) = info_with_idx[i];
        let value = format!("{:06}{:06}",city as i64,city_cnt[city as usize] as i64);
        ans.push((value,idx));
        city_cnt[city as usize] += 1;
    }
    ans.sort_by_key(|&(_,v)| v);
    for (S,_) in ans.into_iter(){
        println!("{}",S);
    }
}

Measured memory_bytes: 17800