n = int(input())
met_info = []
for i in range(n):
met_info.append(list(map(int, input().split())))
met_info = sorted(met_info, key=lambda info: info[0])
met_info = sorted(met_info, key=lambda info: info[1])
meeting_count = 0
start = 0
for meeting in met_info:
if meeting[0] >= start:
start = meeting[1]
meeting_count += 1
print(meeting_count)