#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-7;
const int inf = 0x3f3f3f3f;
const long long linf = 0x3f3f3f3f3f3f3f3fLL;
pair<int, int> pts[1000005];
vector<int> buckets[1005];
bool cmp_up(int a, int b) {
  if (pts[a].second != pts[b].second) return pts[a].second < pts[b].second;
  return pts[a].first < pts[b].first;
}
bool cmp_down(int a, int b) {
  if (pts[a].second != pts[b].second) return pts[a].second > pts[b].second;
  return pts[a].first < pts[b].first;
}
int main() {
  int n;
  scanf("%d", &n);
  for (int i = (0); i < (n); ++i) {
    scanf("%d %d", &pts[i].first, &pts[i].second);
    buckets[pts[i].first / 1000].push_back(i);
  }
  for (int i = (0); i < (1005); ++i)
    sort(buckets[i].begin(), buckets[i].end(), (i & 1) ? cmp_down : cmp_up);
  bool first = true;
  for (int i = (0); i < (1005); ++i) {
    for (int j = (0); j < (buckets[i].size()); ++j) {
      if (!first) putchar(' ');
      first = false;
      printf("%d", buckets[i][j] + 1);
    }
  }
  puts("");
  return 0;
}
