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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>

#define rep(i, n) for(int i = 0; i < (n); ++i)
typedef long long ll;

using namespace std;

typedef struct City
{
  int y, idx;
  City(){};
  City(int a,int b):y(a), idx(b){}
}City;
int main()
{
  int n, m;
  cin >> n >> m;
  vector<vector<City>> P(n);
  rep(i, m)
  {
    int p, y;
    cin >> p >> y;
    P[p-1].emplace_back(City{y, i});
  }
  vector<pair<int, int>> ans(m);
  rep(i, n)
  {
    sort(P[i].begin(), P[i].end(), [](City l, City r){return l.y < r.y;});
    for(int j = 0; j < P[i].size(); ++j)
    {
      ans[P[i][j].idx] = make_pair(i+1, j+1);
    }
  }
  rep(i, m)
    printf("%06d%06d\n", ans[i].first, ans[i].second);

  return 0;
}