import sys as s

x = []
y = []

n = int(input())
for i in range(n):
    a,b = list(map(int, s.stdin.readline().rstrip('\n').split()))
    x.append(a)
    y.append(b)

x.sort()
y.sort()

def check(i):
    if x[i] == x[i-1]:
        return True
    if y[i] == y[i-1]:
        return True

    return False


m = 0

for i in range(1, n):
    if not check(i):
        m += 1

print(int(m))