import std.stdio;
import std.array;
import std.string;
import std.conv;
import std.algorithm;
import std.typecons;
import std.range;

void main() {
  int N = readln().chomp.to!int;
  bool[Tuple!(int, int)] s;
  int ans = 0;
  Tuple!(int, int)[] shuuhen;

  foreach (i; iota(-20, 21))
    foreach (j; iota(-20, 21))
      if (i*i + j*j < 400)
	shuuhen ~= tuple(i, j);

  foreach (i; iota(N)) {
    auto input = readln().split.map!(to!int);
    int x = input[0];
    int y = input[1];
    bool ok = true;
    foreach (t; shuuhen)
      if (tuple(x+t[0], y+t[1]) in s) {
	ok = false;
	break;
      }
    if (ok) {
      s[tuple(x, y)] = true;
      ans += 1;
    }
  }
  writeln(ans);
}