#include <stdio.h>

typedef struct point {
  int x;
  int y;
} point_t;

point_t p[100000];
int pnum;

int N;
int count;

int collision(point_t p, point_t q) {
  return (p.x - q.x) * (p.x - q.x) + (p.y - q.y) * (p.y - q.y) < 20 * 20;
}

int main(void) {
  scanf("%d", &N);
  int i, j;

  for (i = 0; i < N; i++) {
    point_t buf;
    scanf("%d %d", &buf.x, &buf.y);
    for (j = 0; j < pnum; j++) {
      if (collision(buf, p[j])) {
        break;
      }
    }
    if (j == pnum) {
      p[pnum++] = buf;
    }
  }
  printf("%d\n", pnum);
  return 0;
}