#include <bits/stdc++.h>
using namespace std;
struct pairhash {
 public:
  template <typename T, typename U>
  size_t operator()(const pair<T, U> &x) const {
    size_t seed = hash<T>()(x.first);
    return hash<U>()(x.second) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
  }
};
const int inf = 1e9 + 9;
const long long mod = 1e9 + 7;
const double eps = 1e-8;
const double pi = acos(-1);
unsigned long xor128(void) {
  static unsigned long x = 123456789, y = 362436069, z = 521288629,
                       w = 88675123;
  unsigned long t;
  t = (x ^ (x << 11));
  x = y;
  y = z;
  z = w;
  return (w = (w ^ (w >> 19)) ^ (t ^ (t >> 8)));
}
int rand(int k) { return xor128() % k; }
int n;
int x[1000010], y[1000010];
inline int dist(int a, int b) { return abs(x[a] - x[b]) + abs(y[a] - y[b]); }
void solve() {
  vector<int> res;
  vector<int> p[1001];
  for (int i = 0; i < n; i++) {
    p[x[i] / 1000].push_back(i);
  }
  for (int i = 0; i <= 1000; i++) {
    if (i % 2 == 0) {
      sort((p[i]).begin(), (p[i]).end(), [&](const int &a, const int &b) {
        return y[a] < y[b] || (y[a] == y[b] && x[a] < x[b]);
      });
    } else {
      sort((p[i]).begin(), (p[i]).end(), [&](const int &a, const int &b) {
        return y[a] > y[b] || (y[a] == y[b] && x[a] < x[b]);
      });
    }
    for (int j = 0; j < p[i].size(); j++) res.push_back(p[i][j]);
  }
  for (int i = 0; i < n; i++) {
    printf("%d", res[i] + 1);
    if (i < n - 1)
      printf(" ");
    else
      printf("\n");
  }
}
void input() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d%d", &x[i], &y[i]);
  }
}
int main() {
  input();
  solve();
}
