백준-1931

num = int(input())
times = [list(map(int, input().split())) for _ in range(num)]

times.sort(key=lambda x : (x[1], x[0]))
count = 0
end_time = 0


for t in times:
  if end_time <= t[0]:
    end_time = t[1]
    count += 1


print(count)