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: Runtime Error)

#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <map>
 
using namespace std;
using Int = long long int;
using UInt = unsigned long long int;
using VI = vector<long long int>;

struct DATA {
    Int p;
    Int y;
    Int id;
    bool operator< (DATA& d) {
        if (this->p < d.p) {
            return true;
        } else if (this->y < d.y) {
            return true;
        } else {
            return false;
        }
    }
};

int main(void) {
    Int n, m;
    cin >> n >> m;
    Int p, y;
    vector<DATA> v;
    for (Int i = 0; i < m; ++i) {
        cin >> p >> y;
        v.push_back({--p, y, i});
    }
    sort(v.begin(), v.end());

    Int k = 0;
    map<Int, string> mp;
    for (Int i = 0; i < n; ++i) {
        Int j;
        for (j = k; j < m; ++j) {
            if (v[j].p == i) {
                mp[v[j].id] = to_string(v[j].p + 1000001).substr(1, 6) + to_string((j - k + 1) + 1000000).substr(1, 6);
            } else {
                break;
            }
        }
        k = j;
    }
    for (Int i = 0; i < m; ++i) {
        cout << mp[i] << endl;
    }

    return 0;
}