class Ichiendama:
    Radius = 10
    def __init__(self, x, y):
        self.X = int(x)
        self.Y = int(y)

# 2定距離を返す        
def distance2(a, b):
    return ((a.X - b.X)**2 + (a.Y - b.Y)**2)

# 一円玉a, b が重なっていればtrueを返す
def CheckOverlap(a, b):
    if distance2(a,b) < (Ichiendama.Radius*2)**2:
        return True
    else:
        return False

if __name__ == "__main__":

    N = int(input())
    M = 2001
    ans = 0
    Valids = [[ [] for i in range(M)] for j in range(M)]

    for newcoin in range(N):
        (x, y) = input().split()
        (x, y) = (int(x), int(y))
        newcoin = Ichiendama(x, y)
        isOverlap = False
        nx = x//10
        ny = y//10
        neighbor = []
        for i in range(nx-2,nx+3):
            for j in range(ny-2, ny+3):
                neighbor += Valids[i%M][j%M]
        for v in neighbor:
            if CheckOverlap(v, newcoin):
                isOverlap = True
                break
        if isOverlap == False:
            Valids[nx][ny].append(newcoin)
            ans+=1
    print(ans)