n = int(input())
w = []
for i in range(n):
w.append(list(map(int, input().split())))
w.sort()
res = 0
l = w[0][0]
r = w[0][1]
for i in range(1, n):
if w[i][0] <= r:
r = max(r, w[i][1])
else:
res += 1
l = w[i][0]
r = w[i][1]
res += 1
print(res)