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>

using namespace std;

#define INF 210000000
#define int long long

int gcd(int a, int b) {
  int amari = a % b;
  int c = b;
  if (amari == 0) {
    return b;
  } else {
    return gcd(b, amari);
  }
}

int lcm(int a, int b) { return a * b / gcd(a, b); }

struct town {
		int num;
		int y;
		int ken;
		int id = 0;
};
bool cmp(town a,town b){
		if(a.ken != b.ken) return a.ken < b.ken;
		return a.y < b.y;
}
bool cmp_id(town a,town b){
		return a.num < b.num;
}

signed main() {
		int n,m;
		cin >> n >> m;
		vector<town> a;
		for(int i=0;i<m;i++){
				int x,y;
				cin >> x >> y;
				town t;
				t.ken = x;
				t.y = y;
				t.num = i;
				a.push_back(t);
		}
		sort(a.begin(),a.end(),cmp);
		int ken = a[0].ken;
		int id = 1;
		for(auto& A : a){
				if(A.ken == ken) {
						A.id = id;
						id++;
				}else{
						ken = A.ken;
						id = 1;
						A.id = id;
				}
		}
		sort(a.begin(),a.end(),cmp_id);
		for(auto& A : a){
				int z = 6 - ceil((int)A.ken / 10);
				for(int i=0;i<z;i++){
						cout << 0;
				}
				cout << A.ken;
				z = 6 - ceil((int)A.id / 10);
				for(int i=0;i<z;i++){
						cout << 0;
				}
				cout << A.id << endl;
		}
}