#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
clock_t timeStart, timeFinish;
void timeBegin() { timeStart = clock(); }
void timeEnd() { timeFinish = clock(); }
void timeDuration() {
  double time_taken = double(timeFinish - timeStart) / double(CLOCKS_PER_SEC);
  cout << "Time taken by program is : " << fixed << time_taken
       << setprecision(5);
  cout << " sec " << endl;
}
int blo[1000005];
bool fun(const pair<pair<int, int>, int> &x,
         const pair<pair<int, int>, int> &y) {
  if (blo[x.first.first] != blo[y.first.first]) {
    return blo[x.first.first] < blo[y.first.first];
  }
  if (blo[x.first.first] % 2) {
    return x.first.second > y.first.second;
  } else {
    return x.first.second < y.first.second;
  }
}
void solve() {
  int n;
  cin >> n;
  int x[n + 3], y[n + 3];
  vector<pair<pair<int, int>, int>> v;
  for (int i = 1; i <= n; i++) {
    cin >> x[i] >> y[i];
    v.push_back({{x[i], y[i]}, i});
  }
  for (int i = 0; i <= 1000000; i++) {
    blo[i] = i / 1000;
  }
  sort(v.begin(), v.end(), fun);
  for (int i = 0; i < n; i++) cout << v[i].second << " ";
  cout << '\n';
  return;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t = 1;
  while (t--) solve();
  return 0;
}
