n = int(input())
r = []
R = []
for _ in range(n):
    ri, Ri = map(int, input().split())
    r.append(ri)
    R.append(Ri)
r.sort(reverse=True)
R.sort()
ans = n - 1
for Ri in R:
    while r and r[-1] < Ri:
        r.pop()
    if r:
        ans -= 1
        r.pop()
print(ans)