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 C++ (GCC 9.2.1) (judge verdict: Accepted)

#include <algorithm>
#include <bitset>
#include <cmath>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <vector>
#define ll long long
using namespace std;
const int MOD = 1000000007;
const long long INF = 1LL << 60;
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll n, m;
  cin >> n >> m;
  vector<ll> p(m);
  vector<ll> y(m);
  vector<tuple<ll, ll, ll>> s;
  for (ll i = 0; i < m; i++) {
    cin >> p[i] >> y[i];
    s.emplace_back(p[i], y[i], i);
  }
  sort(s.begin(), s.end());
  // for (ll i = 0; i < m; i++) {
  //   tuple<ll, ll, ll> t = s[i];
  //   cout << get<0>(t) << " " << get<1>(t) << " " << get<2>(t) << endl;
  // }
  map<ll, ll> mp;
  vector<pair<ll, string>> ans;
  for (auto x : s) {
    // cout << get<0>(x) << " " << get<1>(x) << " " << get<2>(x) << endl;
    string f = "000000";
    string b = "000000";
    ll city = get<0>(x);
    mp[city]++;
    for (ll i = 5; i >= 0; i--) {
      ll num = city % 10;
      f[i] = num + '0';
      city /= 10;
    }
    ll city_num = mp[get<0>(x)];
    for (ll i = 5; i >= 0; i--) {
      ll num = city_num % 10;
      b[i] = num + '0';
      city_num /= 10;
    }
    ans.push_back(pair<ll, string>(get<2>(x), f + b));
  }
  sort(ans.begin(), ans.end());
  for (auto x : ans) {
    cout << x.second << endl;
  }
}