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
//package practice;
/**
 * Created by Rajan Waliya on 11-Sep-15.
 */
import java.io.*;
import java.util.*;
/*
the idea is to traverse like this : or the opposite way
     ___     ___
    |   |   |   |   |
    |   |   |   |   |
    |   |___|   |___|

 */

//public
class C576 {

    Reader sc;
    PrintWriter out;

    void solve() throws IOException {
        int n = sc.nextInt();
        point[] a = new point[n];
        for(int i=0;i<n;i++){
            a[i]= new point(sc.nextInt(),sc.nextInt(),i+1);
        }
        Arrays.sort(a);
        StringBuilder sb = new StringBuilder();
        for(point p:a){
            sb.append(p.ind).append(" ");
        }
        out.println(sb);
    }

    class point implements Comparable<point>{
        int x,y,ind;
        public point(int a,int b,int c){
            x=a;y=b;ind=c;
        }
        @Override
        public int compareTo(point o) {
            if((this.x/1000)!=(o.x/1000)){
                return Integer.compare(this.x,o.x);
            }
            else{
                if((this.x/1000)%2==0){//even
                    return  -Integer.compare(this.y,o.y);
                }else{
                    return Integer.compare(this.y,o.y);
                }
            }
        }
    }



    //_______congratulation!!! main logic has ended, no need to understand what is after this line.________
    void runIO() throws Exception {
        sc = new Reader();
        out = new PrintWriter(System.out);
        solve();
        out.close();
    }

    public static void main(String[] args) throws Exception {
        new C576().runIO();
    }

    static class Reader {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Reader() {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) throws IOException {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException {
            byte[] buf = new byte[64];
            int cnt = 0, c;
            while ((c = read()) != -1) {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10L + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
            if (c == '.')
                while ((c = read()) >= '0' && c <= '9')
                    ret += (c - '0') / (div *= 10);
            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public String next() throws IOException {
            StringBuilder sb = new StringBuilder();
            byte c;
            while ((c = read()) <= ' ') ;
            do {
                sb.append((char) c);
            } while ((c = read()) > ' ');
            return sb.toString();
        }

        public int nextInt2() throws IOException {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public void close() throws IOException {
            if (din == null)
                return;
            din.close();
        }
    }

}