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 <string>
#include <cstring>
#include <queue>
#include <set>
#include <stack>
#include <map>
#include <unordered_map>
#include <cmath>
#include <utility> // pair make_pair
#include <algorithm>
#include <functional>
#include <iomanip>
#include <numeric>
#include <climits> // LLONG_MAX, LLONG_MIN, INT_MIN, INT_MAX
#include <assert.h>

#define m0(x) memset(x,0,sizeof(x))
#define m1(x) memset(x,63,sizeof(x))
#define fill(x,y) memset(x,y,sizeof(x))
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define ll long long
//#define int ll
#define INF INT_MAX/10
#define MOD 1000000007

using namespace std;
using Pi = pair<int, int>;
using Graph = vector<vector<int> >;
using WeightGraph = vector<vector<Pi> >;

int Input[100100];

int main() {
  int N, M; cin >> N >> M;
  vector<int> P(M), Y(M);

  rep(i, M) {
    cin >> P[i] >> Y[i], --P[i];
  }

  vector<vector<int>> vals(N);
  for (int i = 0; i < M; i++) {
    vals[P[i]].push_back(Y[i]);
  }

  rep(i, N) {
    sort(vals[i].begin(), vals[i].end());
  }

  rep(i, M) {
    int v = P[i];
    printf("%06d", v + 1);
    int id = lower_bound(vals[v].begin(), vals[v].end(), Y[i]) - vals[v].begin();
    printf("%06d\n", id + 1);
  }
  
}