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: Accepted)

#include<stdio.h>
#include<stdlib.h>
typedef unsigned u;
u *G[111111],Ga[111111],Gi[111111];
u *N[111111],Gu[111111];
void add(u i,u j)
{
	if(Ga[i]==Gi[i])
	{
		if(!Ga[i])
		{
			Ga[i]=1;
			G[i]=(u*)calloc(Ga[i],sizeof(u));
			N[i]=(u*)calloc(Ga[i],sizeof(u));
		}
		else
		{
			Ga[i]<<=1;
			G[i]=(u*)realloc(G[i],Ga[i]*sizeof(u));
			N[i]=(u*)realloc(N[i],Ga[i]*sizeof(u));
		}
	}
	N[i][Gi[i]]=Gi[i];
	G[i][Gi[i]++]=j;
	return;
}
u X[111111],Y[111111],z;
int F(const void*x,const void*y){return G[z][*(u*)x]-G[z][*(u*)y];}
int main()
{
	u n,m,i,x,y;
	scanf("%u%u",&n,&m);
	for(i=-1;++i<m;)
	{
		scanf("%u%u",&x,&y);
		X[i]=x;Y[i]=y;
		add(x,y);
	}
	for(z=0;z++<n;)
	{
		qsort(N[z],Gi[z],sizeof(u),F);
		for(i=-1;++i<Gi[z];)G[z][N[z][i]]=i+1;
	}
	for(i=-1;++i<m;)
	{
		x=X[i];y=G[x][Gu[x]++];
		printf("%.6u%.6u\n",x,y);
	}
	return 0;
}