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<bits/stdc++.h>
using namespace std;
using ll = long long;
using product = pair<ll,ll>;
using vvll = vector<vector<ll>>;
using vll = vector<ll>;

int main()
{
    ll N,M;
    cin>>N>>M;
    vll P(M);
    vll Y(M);
    for(ll i=0;i<M;i++)
    {
        cin>>P[i]>>Y[i];
        --P[i];
    }
    vvll vals(N);
    for(ll i=0;i<M;i++)vals[P[i]].emplace_back(Y[i]);
    for(ll i=0;i<N;i++)sort(vals[i].begin(),vals[i].end());

    for(ll i=0;i<M;i++)
    {
        ll v=P[i];
        printf("%06d",v+1);

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