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: Wrong Answer)

#include <bits/stdc++.h>
#define ll long long
using namespace std;

int digit(int x){
  int y=0;
  while(x>0){
    y++;
    x/=10;
  }
  return y;
}

int main(){
  int n,m;
  cin>>n>>m;
  vector<pair<int,ll>> vec(m);
  vector<pair<int,ll>> vecb(m);
  for(int i=0;i<m;i++){
    int j;
    ll k;
    cin>>j>>k;
    vec[i]=make_pair(j,k);
    vecb[i]=vec[i];
  }
  sort(vecb.begin(),vecb.end());
  map<pair<int,ll>,int> ma;
  for(int i=0;i<m;i++){
    if(i==0){
      ma[vecb[i]]=1;
    }
    else{
      if(vecb[i].first==vecb[i-1].first){
        ma[vecb[i]]=ma[vecb[i-1]]+1;
      }
      else{
        ma[vecb[i]]=1;
      }
    }
  }
  for(int i=0;i<m;i++){
    for(int i=0;i<6-digit(vec[i].first);i++){
      cout<<0;
    }
    cout<<vec[i].first;
    for(int i=0;i<6-digit(ma[vec[i]]);i++){
      cout<<0;
    }
    cout<<ma[vec[i]]<<endl;
  }
}