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 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>

int main(){
	long long N,M,i;
	scanf("%lld%lld",&N,&M);
	long long P[M],Y[M],C[M],A[M];
	long long count[N+1];
	for(i=0;i<M;i++){
		scanf("%lld%lld",&P[i],&Y[i]);
		C[i]=i;
	}
	for(i=0;i<=N;i++)count[i]=0;
	
	//sort
	long long h=N;
	long long swapped=0;
	while(h>1 || swapped==1){
		if(h>1)h=h*10/13;
		swapped=0;
		for(i=0;i<M-h;i++){
			if(Y[i]>Y[i+h]){
				long long tmp=Y[i];
				Y[i]=Y[i+h];
				Y[i+h]=tmp;
				tmp=P[i];
				P[i]=P[i+h];
				P[i+h]=tmp;
				tmp=C[i];
				C[i]=C[i+1];
				C[i+1]=tmp;
				swapped=1;
			}
		}
	}
	
	for(i=0;i<M;i++){
		count[P[i]]++;
		A[C[i]]=P[i]*1000000+count[P[i]];
	}
	for(i=0;i<M;i++){
		if(A[i])
		printf("%012lld\n",A[i]);
	}	
	return 0;
}