import sys
input = sys.stdin.readline
from heapq import heappush,heappop

N = int(input())
meetings = []
for i in range(N):
    a,b = map(int,input().split())
    heappush(meetings, (b,a))
	
end_time = 0
cnt=0
while meetings:
    if meetings[0][1]>=end_time:
        cnt+=1
        end_time = heappop(meetings)[0]
        continue
    heappop(meetings)
print(cnt)