#include <bits/stdc++.h>
template <class Num>
void read(Num &x) {
  char c;
  int flag = 1;
  while ((c = getchar()) < '0' || c > '9')
    if (c == '-') flag *= -1;
  x = c - '0';
  while ((c = getchar()) >= '0' && c <= '9')
    x = (x << 3) + (x << 1) + (c - '0');
  x *= flag;
}
template <class Num>
void write(Num x) {
  if (!x) {
    putchar('0');
    return;
  }
  if (x < 0) putchar('-'), x = -x;
  static char s[20];
  int sl = 0;
  while (x) s[sl++] = x % 10 + '0', x /= 10;
  while (sl) putchar(s[--sl]);
}
const int maxn = 1e6 + 20;
const int size = 1e3;
int n;
std::pair<std::pair<int, int>, int> rev[maxn];
bool cmp(const std::pair<std::pair<int, int>, int> &a,
         const std::pair<std::pair<int, int>, int> &b) {
  return a.first.second < b.first.second;
}
int main() {
  read(n);
  for (int i = 1, x, y; i <= n; i++) {
    read(x), read(y);
    rev[i] = std::make_pair(std::make_pair(y, x), i);
  }
  std::sort(rev + 1, rev + n + 1, cmp);
  for (int i = 1, pos = 1; i <= size; i++) {
    int st = pos;
    while (pos <= n && rev[pos].first.second <= i * size) pos++;
    if (i & 1)
      std::sort(rev + st, rev + pos);
    else
      std::sort(rev + st, rev + pos,
                std::greater<std::pair<std::pair<int, int>, int> >());
  }
  for (int i = 1; i <= n; i++) write(rev[i].second), putchar(' ');
  return 0;
}
