#include <iostream>
#include <fstream>
#include <sstream>

#include <vector>
#include <set>
#include <bitset>
#include <map>
#include <deque>
#include <string>

#include <algorithm>
#include <numeric>

#include <cstdio>
#include <cassert>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <cmath>

#define pb push_back
#define pbk pop_back
#define mp make_pair
#define fs first
#define sc second
#define all(x) (x).begin(), (x).end()
#define foreach(i, a) for (__typeof((a).begin()) i = (a).begin(); i != (a).end(); ++i)
#define len(a) ((int) (a).size())

#ifdef CUTEBMAING
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define eprintf(...) 42
#endif

using namespace std;

typedef long long int64;
typedef long double ld;
typedef unsigned long long lint;

const int inf = (1 << 30) - 1;
const int64 linf = (1ll << 62) - 1;
const int C = 1000;

int main() {
    int n; cin >> n;
    vector<pair<pair<int, int>, int>> points(n);
    for (int i = 0; i < n; i++) {
        scanf("%d%d", &points[i].fs.fs, &points[i].fs.sc);
        points[i].sc = i;
        points[i].fs.fs /= C;
    }
    sort(all(points), [](const pair<pair<int, int>, int> &a, const pair<pair<int, int>, int> &b) {
        return a.fs.fs < b.fs.fs || (a.fs.fs == b.fs.fs && (a.fs.fs % 2 == 0 ? (a.fs.sc < b.fs.sc) : (a.fs.sc > b.fs.sc)));
    });
    for (auto i : points) {
        printf("%d ", i.sc + 1);
    }
    puts("");
    return 0;
}