import sys
input = sys.stdin.readline

from operator import itemgetter
from heapq import heappop,heappush

N=int(input())
AB=[list(map(int,input().split())) for i in range(N)]

AB.sort(key=itemgetter(0))
H=[]

for a,b in AB:
    if H:
        if H[0]<=a:
            heappop(H)
            heappush(H,b)
        else:
            heappush(H,b)
    else:
        heappush(H,b)

print(len(H)-1)