import java.io.IOException; import java.util.ArrayList; import java.util.InputMismatchException; public class Main { class Point implements Comparable { int x, y; Point(int x, int y) { this.x = x; this.y = y; } @Override public int compareTo(Point o) { return this.x != o.x ? this.x - o.x : this.y - o.y; } } boolean isIntersect(Point a, Point b) { return (a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y) < 400; } void run() { MyScanner sc = new MyScanner(); ArrayList[] X = new ArrayList[20001]; ArrayList[] Y = new ArrayList[20001]; for (int i = 0; i < 20001; i++) { X[i] = new ArrayList(); Y[i] = new ArrayList(); } int n = sc.nextInt(); int ans = 0; L: for (int i = 0; i < n; i++) { int x = sc.nextInt(); int y = sc.nextInt(); Point p = new Point(x, y); int maxY = Math.min(20000, y + 19); for (int j = Math.max(0, y - 19); j <= maxY; j++) { for (Point q : Y[j]) { if (isIntersect(p, q)) { continue L; } // if (p.x < q.x && !isIntersect(p, q)) { // break; // } } } int maxX = Math.min(20000, x + 19); for (int j = Math.max(0, x - 19); j <= maxX; j++) { for (Point q : X[j]) { if (isIntersect(p, q)) { continue L; } // if (p.y < q.y && !isIntersect(p, q)) { // break; // } } } X[x].add(p); Y[y].add(p); ans++; } System.out.println(ans); } public static void main(String[] args) { new Main().run(); } public void mapDebug(int[][] a) { System.out.println("--------map display---------"); for (int i = 0; i < a.length; i++) { for (int j = 0; j < a[i].length; j++) { System.out.printf("%3d ", a[i][j]); } System.out.println(); } System.out.println("----------------------------" + '\n'); } class MyScanner { int read() { try { return System.in.read(); } catch (IOException e) { throw new InputMismatchException(); } } boolean isSpaceChar(int c) { return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1; } boolean isEndline(int c) { return c == '\n' || c == '\r' || c == -1; } int nextInt() { return Integer.parseInt(next()); } int[] nextIntArray(int n) { int[] array = new int[n]; for (int i = 0; i < n; i++) array[i] = nextInt(); return array; } long nextLong() { return Long.parseLong(next()); } long[] nextLongArray(int n) { long[] array = new long[n]; for (int i = 0; i < n; i++) array[i] = nextLong(); return array; } double nextDouble() { return Double.parseDouble(next()); } double[] nextDoubleArray(int n) { double[] array = new double[n]; for (int i = 0; i < n; i++) array[i] = nextDouble(); return array; } String next() { int c = read(); while (isSpaceChar(c)) c = read(); StringBuilder res = new StringBuilder(); do { res.appendCodePoint(c); c = read(); } while (!isSpaceChar(c)); return res.toString(); } String[] nextStringArray(int n) { String[] array = new String[n]; for (int i = 0; i < n; i++) array[i] = next(); return array; } String nextLine() { int c = read(); while (isEndline(c)) c = read(); StringBuilder res = new StringBuilder(); do { res.appendCodePoint(c); c = read(); } while (!isEndline(c)); return res.toString(); } } }