from bisect import bisect_left as lower_bound
from bisect import bisect_right as upper_bound
class FenwickTree:
 def __init__(self,x):
  bit=self.bit=list(x)
  size=self.size=len(bit)
  for i in range(size):
   j=i|(i+1)
   if j<size:
    bit[j]+=bit[i]

 def update(self,idx,x):
  """updates bit[idx]+=x"""
  while idx<self.size:
   self.bit[idx]+=x
   idx|=idx+1

 def __call__(self,end):
  """calc sum(bit[:end])"""
  x=0
  while end:
   x+=self.bit[end-1]
   end&=end-1
  return x

 def find_kth(self,k):
  """Find largest idx such that sum(bit[:idx])<=k"""
  idx=-1
  for d in reversed(range(self.size.bit_length())):
   right_idx=idx+(1<<d)
   if right_idx<self.size and self.bit[right_idx]<=k:
    idx=right_idx
    k-=self.bit[idx]
  return idx+1,k


class SortedList:
 block_size=700

 def __init__(self,iterable=()):
  self.macro=[]
  self.micros=[[]]
  self.micro_size=[0]
  self.fenwick=FenwickTree([0])
  self.size=0
  for item in iterable:
   self.insert(item)

 def insert(self,x):
  i=lower_bound(self.macro,x)
  j=upper_bound(self.micros[i],x)
  self.micros[i].insert(j,x)
  self.size+=1
  self.micro_size[i]+=1
  self.fenwick.update(i,1)
  if len(self.micros[i]) >= self.block_size:
   self.micros[i:i+1]=self.micros[i][:self.block_size >> 1],self.micros[i][self.block_size >> 1:]
   self.micro_size[i:i+1]=self.block_size >> 1,self.block_size >> 1
   self.fenwick=FenwickTree(self.micro_size)
   self.macro.insert(i,self.micros[i+1][0])

 def pop(self,k=-1):
  i,j=self._find_kth(k)
  self.size-=1
  self.micro_size[i]-=1
  self.fenwick.update(i,-1)
  return self.micros[i].pop(j)

 def __getitem__(self,k):
  i,j=self._find_kth(k)
  return self.micros[i][j]

 def count(self,x):
  return self.upper_bound(x)-self.lower_bound(x)

 def __contains__(self,x):
  return self.count(x)>0

 def lower_bound(self,x):
  i=lower_bound(self.macro,x)
  return self.fenwick(i)+lower_bound(self.micros[i],x)

 def upper_bound(self,x):
  i=upper_bound(self.macro,x)
  return self.fenwick(i)+upper_bound(self.micros[i],x)

 def _find_kth(self,k):
  return self.fenwick.find_kth(k+self.size if k<0 else k)

 def __len__(self):
  return self.size

 def __iter__(self):
  return (x for micro in self.micros for x in micro)

 def __repr__(self):
  return str(list(self))
(n,),*e=[[*map(int,s.split())]for s in open(0)]
p=SortedList()
for r,R in sorted(e):
  i=p.upper_bound(r)-1
  if 0<=i<len(p):
    p.pop(i)
  p.insert(R)
print(len(p)-1)