#!/usr/bin/env python
import sys
N=int(input())
meze=[]

for i in range(N):
   (a,b)=raw_input().split()
   meze.append((int(a),int(b)))
meze.sort(key=lambda meze: meze[1])

vys=0
pos=0
for z,k in meze:
    if z>pos:
         vys+=1
         pos=k
print vys