import heapq

N = int(input())
A = [tuple(map(int, input().split())) for _ in range(N)]
A.sort()
q = []

for l, r in A:
    if q and q[0] <= l:
        heapq.heappop(q)
    heapq.heappush(q, r)

print(len(q) - 1)