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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <iostream>
#include <cmath>
#include <string>
#include <cstring>
#include <utility>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#define debug(x) cerr << #x << ':' << x << endl
#define REP(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
using namespace std;
typedef long long ll;

struct info{
    int ci;
    int pref;
    int year;
    string id="";
    info(int i, int p, int y){
        ci = i;
        pref = p;
        year = y;
    }
};

bool comp1(const info &a, const info &b){
    if(a.pref==b.pref){
        return a.year < b.year;
    }
    else
        return a.pref < b.pref;
}

bool comp2(const info &a, const info &b){
    return a.ci < b.ci;
}

int main(){
    int n,m;
    cin >> n >> m;
    vector<info> A;
    REP(i,m){
        int p, y;
        cin >> p >> y;
        string s;
        A.push_back(info(i, p, y));
    }
    sort(ALL(A), comp1);
    int order=0;
    int past=-1;
    for(int i=0; i<m; i++){
        if(A[i].pref==past)
            order+=1;
        else
            order = 1;

        string s1;
        REP(i,6-to_string(A[i].pref).size()) s1.append("0");
        s1.append(to_string(A[i].pref));

        string s2;
        REP(i,6-to_string(order).size()) s2.append("0");
        s2.append(to_string(order));
        A[i].id = s1 + s2;
        past = A[i].pref;
    }
    sort(ALL(A), comp2);

    for(auto x : A)
        cout << x.id<< endl;
    return 0;
}