#include <bits/stdc++.h>
using namespace std;
struct node {
  int x, y, id;
} a[1000005];
const bool cmp(const node &i, const node &j) { return i.x < j.x; }
const bool cmp1(const node &i, const node &j) { return i.y < j.y; }
vector<node> v;
vector<int> ans;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  while (cin >> n) {
    ans.clear();
    int x, y;
    for (int i = 1; i <= n; i++) {
      cin >> a[i].x >> a[i].y;
      a[i].id = i;
    }
    int sqrn = sqrt(1000005);
    sort(a + 1, a + n + 1, cmp);
    int j = 1;
    for (int i = sqrn; i <= 1000005; i += sqrn) {
      v.clear();
      while (j <= n && a[j].x <= i) {
        v.push_back(a[j]);
        j++;
      }
      sort(v.begin(), v.end(), cmp1);
      for (auto p : v) {
        ans.push_back(p.id);
      }
    }
    for (auto i : ans) {
      printf("%d ", i);
    }
    printf("\n");
  }
  return 0;
}
