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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <iostream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <queue>
#include <list>
#include <limits>
#include <string>
#include <vector>
using namespace std;
 
typedef long long ll;
typedef pair<int, int> P;
const int MOD = 998244353;

struct cell{
  int no;
  ll year;
};
bool operator<(const cell& left, const cell& right){
  return left.year < right.year;
}
bool operator>(const cell& left, const cell& right){
  return left.year > right.year;
}

int gcd(int a, int b){
  if(b == 0) return a;
  return gcd(b, a%b);
}

int main()
{
  int N,M,p;
  int m[100000];
  ll num;
  cin >> N >> M;
  struct cell ncell;
  vector<cell> years[100001];
  for(int i=0;i<M;i++){
    cin >> p >> num;
    ncell.no = i;
    ncell.year = num;
    m[i] = p;
    years[p].push_back(ncell);
  }  
  for(int i=0;i<N;i++){
    sort(years[i].begin(),years[i].end());
  }
  for(int i=0;i<M;i++){
    ll j=m[i];
      for(int k=0;k<years[j].size();k++){
        if(years[j][k].no == i){
          num = j*1000000+k+1;
          cout << setfill('0') << setw(12) << right << num << endl;   
        } 
    }
  }
}