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 <algorithm>
#include <vector>

using namespace std;

void print_s(int k){
    int keta = 1;
    while(k > 10){
        k /= 10;
        keta++;
    }
    for(int i = 6; i > keta; i--)cout << "0" << flush;
    cout << k ;
}

int main(){
    int n,m; cin >> n >> m;
    int p, y;
    vector<vector<int>> c;
    c = vector<vector<int>>(m);
    vector<pair<int,int>> list;
    for(int i = 0; i < m; i++){
        cin >> p >> y;
        pair<int,int> pp;
        c[p].push_back(y);
        pp.first = p;
        pp.second = y;
        list.push_back(pp);
    }

    string s = "00000";
    for(int i = 0 ;i < m; i++){
        sort(c[i].begin(), c[i].end());
        for(int j = 0; j < c[list[i].first].size(); j++){
            if(list[i].second == c[list[i].first][j]){
                //cout <<  s + char(list[i].first + '0') << s +  char(j+1 + '0') << endl;
                print_s(list[i].first);
                print_s(j+1);
                cout << endl;
                break;
            }
        }
    }
    return 0;
}