import sys
def dfs(cx,cy,hx,hy):
	ones.add((hx,hy))
	for i in range(4):
		nx = hx + dx[i]; ny = hy + dy[i]
		if (nx,ny) not in ones and (cx-nx)**2 + (cy-ny)**2 < 400:
			dfs(cx,cy,nx,ny)
dx = (1,0,-1,0)
dy = (0,1,0,-1)
sys.setrecursionlimit(10000000)
ones = set()
N = int(raw_input())
ans = 0
for i in range(N):
	x,y = map(int,raw_input().split(" "))
	if (x,y) not in ones:
		ans += 1
		dfs(x,y,x,y)
print ans