(n,),*e=[[*map(int,s.split())]for s in open(0)]
rs=[]
for r,R in e:
  rs+=(r,R),
rs.sort()
ans=0
nr=[]
while rs:
  l=0
  for r,R in rs:
    if l<=r:
      l=R
    else:
      nr+=(r,R),
    # print(R,r,rs,nr)
  if nr:
    ans+=1
  rs,nr=nr,[]
print(ans)