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 fi first
#define se second
#define pb push_back
#define mp make_pair
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define all(s) s.begin(), s.end()
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
const int MX = 100005, INF = 1001001001;
const ll LINF = 1e18;
const double eps = 1e-10;
const int DIV = 1e9+7;

struct data {
    int id;
    int pref;
    int year;
    int ord;
};
bool year_asc(const data& left, const data& right) {
    return left.year < right.year;
}
bool id_asc(const data& left, const data& right) {
    return left.id < right.id;
}

int main() {
    int n, m;
    cin >> n >> m;
    vector<data> datas;
    rep(i, m) {
        int p, y;
        cin >> p >> y;
        data d = {i, p, y, 0};
        datas.pb(d);
    }
    sort(datas.begin(), datas.end(), year_asc);

    vi nums(n, 0);
    rep(i, m) datas[i].ord = ++nums[datas[i].pref];

    sort(datas.begin(), datas.end(), id_asc);
    for (auto d: datas) {
        cout << setfill('0') << right << setw(6) << d.pref;
        cout << setfill('0') << right << setw(6) << d.ord << endl;
    }
}