def distance(X, Y):
    return abs(X[0] - Y[0]) + abs(X[1] - Y[1])

n = int(input())
f = list(map(int, input().split()))
xy = [list(map(int, input().split())) for _ in range(n-1)]

delete = set()

for i in range(n-1):
    fd = distance(f, xy[i])
    explotion = False

    for g in range(n-1):
        if g in delete or g == i:
            continue
        d = distance(xy[i], xy[g])
        if fd > d:
            explotion = True
            break

    if not explotion:
        delete.add(i)

print(len(delete))