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: Runtime Error)

#include <iostream>
#include <vector>
#include <algorithm>
#include <ios>
#include <iomanip>

using namespace std;
using ll = long long;
using P = pair<int,int>;
const int MOD = 1e9+7;
#define put(n) cout<<(n)<<endl
#define rep(i,N) for(int(i)=0;(i)<(N);++(i))
#define rrep(i,N) for(int (i)=(N-1);(i)>=(0);--(i))
#define all(v) (v).begin() , (v).end()
#define rall(v) (v).rbegin() , (v).rend()
#define pb(n) push_back(n)

int main(){
    int N,M;
    cin >> N >> M;
    vector<vector<P>> city(N+1);
    vector<int> ans1(N),ans2(N);

    rep(i,M){
        int a,b;
        cin >> a >> b;
        city[a].push_back({b,i});
    }

    rep(i,N+1){
        if(city[i].size() < 1) continue;
        sort(all(city[i]));
    }

    rep(i,N+1){
        rep(j,city[i].size()){
            P c = city[i][j];
            ans1[c.second] = i;
            ans2[c.second] = j+1;
        }
    }

    rep(i,M){
        cout << setfill('0') << right << setw(6) << ans1[i];
        cout << setfill('0') << right << setw(6) << ans2[i] << endl;
    }

}