On a plane are n points (xi, yi) with integer coordinates between 0 and 106. The distance between the two points with numbers a and b is said to be the following value: <image> (the distance calculated by such formula is called Manhattan distance).

We call a hamiltonian path to be some permutation pi of numbers from 1 to n. We say that the length of this path is value <image>.

Find some hamiltonian path with a length of no more than 25 × 108. Note that you do not have to minimize the path length.

Input

The first line contains integer n (1 ≤ n ≤ 106).

The i + 1-th line contains the coordinates of the i-th point: xi and yi (0 ≤ xi, yi ≤ 106).

It is guaranteed that no two points coincide.

Output

Print the permutation of numbers pi from 1 to n — the sought Hamiltonian path. The permutation must meet the inequality <image>.

If there are multiple possible answers, print any of them.

It is guaranteed that the answer exists.

Examples

Input

5
0 7
8 10
3 4
5 0
9 12


Output

4 3 1 2 5 

Note

In the sample test the total distance is:

<image>

(|5 - 3| + |0 - 4|) + (|3 - 0| + |4 - 7|) + (|0 - 8| + |7 - 10|) + (|8 - 9| + |10 - 12|) = 2 + 4 + 3 + 3 + 8 + 3 + 1 + 2 = 26
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Locale;
import java.util.StringTokenizer;

public class E {

	private static BufferedReader in;
	private static StringTokenizer st;
	private static PrintWriter out;

	private static class Point implements Comparable<Point>{
		
		public int x,y, ind;
		
		@Override
		public int compareTo(Point o) {
			return this.y - o.y;
		}
		public Point(int a, int b, int i) {
			x = a;
			y = b;
			ind = i;
		}
	}
	public static void main(String[] args) throws NumberFormatException, IOException {
		Locale.setDefault(Locale.US);
		in = new BufferedReader(new InputStreamReader(System.in));
		st = new StringTokenizer("");
		out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
		int n = nextInt();
		Point p[] = new Point[n];
		for (int i = 0; i < n; i++) {
			p[i] = new Point(nextInt(), nextInt(), i+1);
		}
		ArrayList<Point> rect[] = new ArrayList[1001];
		for (int i = 0; i <=1000; i++) {
			rect[i] =  new ArrayList<Point>();
		}
		for (int i = 0; i < n; i++) {
			int num = p[i].x / 1000;
			rect[num].add(p[i]);
		}
		for (int i = 0; i < rect.length; i++) {
			Collections.sort(rect[i]);
		}
		int ind = 0;
		ArrayList<Integer> list = new ArrayList<Integer>();
		for (int i = 0; i < rect.length; i++) {
			if(!rect[i].isEmpty()){
				ind++;
				if(ind % 2 == 1){
					for (int j = 0; j < rect[i].size(); j++) {
						list.add(rect[i].get(j).ind);
					}
				}else{
					for (int j = rect[i].size()-1; j >= 0; j--) {
						list.add(rect[i].get(j).ind);
					}
				}
			}
		}
		for (int i : list) {
			out.print(i+" ");
		}
		out.close();
	}

	private static double nextDouble() throws NumberFormatException, IOException {
		return Double.parseDouble(next());
	}

	private static long nextLong() throws NumberFormatException, IOException {
		return Long.parseLong(next());
	}

	private static int nextInt() throws NumberFormatException, IOException {
		return Integer.parseInt(next());
	}

	private static String next() throws IOException {
		while(!st.hasMoreTokens())
			st = new StringTokenizer(in.readLine());
		return st.nextToken();
	}
}
