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