from sys import stdin

n = int(stdin.readline())

matryoshka_list = [list(map(int, stdin.readline().split())) for _ in range(n)]

matryoshka_list = sorted(matryoshka_list, reverse=True, key=lambda x: (x[1],x[0]))

res = 0

while len(matryoshka_list) > 1:
	r_in = matryoshka_list[-1][1]
	for i in range(len(matryoshka_list)-2, -1, -1):
		if r_in <= matryoshka_list[i][0]:
			del matryoshka_list[-1]
			break
	res += 1
	del matryoshka_list[-1]

print(res)