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 <bits/stdc++.h>
using namespace std;
int s[100000],s1[100000];
vector<int> t[100000];
string f(int x){
    if(x<10)return "0000";
    else if(x<100)return "000";
    else if(x<1000)return "00";
    else if(x<10000)return "0";
    else return "";
}
int main(void){
    int n,k;
    cin>>n>>k;
    
    for(int i=0;i<k;i++){
        cin>>s[i];
        cin>>s1[i];
        t[s[i]].push_back(s1[i]);
    }
    for(int i=0;i<n;i++){
        if(!t[n].empty()){
        sort(t[i].begin(),t[i].end());
        }
    }
    //cout<<t[1][1]<<endl;
    
    for(int i=0;i<k;i++){
        cout<<f(s[i])<<s[i];
        int mid=lower_bound(t[s[i]].begin(),t[s[i]].end(),s1[i])-t[s[i]].begin();
        cout<<f(mid+1)<<mid+1<<endl;
    }
    //cout<<f(100000)<<endl;
}