#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-6;
const int INF = 0x3f3f3f3f, N = 2000005, M = 2000005, MOD = 1e9 + 7;
int sgn(double x) { return x < -eps ? -1 : (x < eps ? 0 : 1); }
int Rand(int x) { return rand() * rand() % x + 1; }
struct node {
  int x, y, bel, id;
} a[N];
int Solve() {
  int n;
  cin >> n;
  int sn = sqrt(1000000);
  for (int i = 1; i <= n; i++) {
    cin >> a[i].x >> a[i].y;
    a[i].bel = a[i].x / sn;
    a[i].id = i;
  }
  sort(a + 1, a + 1 + n, [](node a, node b) {
    if (a.bel != b.bel) return a.bel < b.bel;
    if (a.bel & 1)
      return a.y < b.y;
    else
      return a.y > b.y;
  });
  for (int i = 1; i <= n; i++) {
    cout << a[i].id;
    if (i == n)
      cout << '\n';
    else
      cout << " ";
  }
  return 0;
}
void Pre() {}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0), cout.tie(0);
  Pre();
  while (Solve())
    ;
  return 0;
}
