class SegTree:
    def __init__(self, op, e, n, v=None):
        self._n = n
        self._op = op
        self._e = e
        self._log = (n - 1).bit_length()
        self._size = 1 << self._log
        self._d = [self._e] * (2 * self._size)
        if v is not None:
            for i in range(self._n):
                self._d[self._size + i] = v[i]
            for i in range(self._size - 1, 0, -1):
                self._update(i)
    
    def set(self, p, x):
        assert 0 <= p < self._n
        p += self._size
        self._d[p] = x
        for i in range(1, self._log + 1):
            self._update(p >> i)
    
    def get(self, p):
        assert 0 <= p < self._n
        return self._d[p + self._size]
 
    def prod(self, l, r):
        assert 0 <= l <= r <= self._n
        sml, smr = self._e, self._e
        l += self._size
        r += self._size
        while l < r:
            if l & 1:
                sml = self._op(sml, self._d[l])
                l += 1
            if r & 1:
                r -= 1
                smr = self._op(self._d[r], smr)
            l >>= 1
            r >>= 1
        return self._op(sml, smr)
    
    def all_prod(self):
        return self._d[1]
 
    def _update(self, k):
        self._d[k] = self._op(self._d[2 * k], self._d[2 * k + 1])
#https://qiita.com/AkariLuminous/items/32cbf5bc3ffb2f84a898
N=int(input())
Q=[]
for i in range(N):
  r,R=list(map(int,input().split()))
  Q.append((r,R))
Q=sorted(Q)
maxr=Q[-1][0]
check=set()
ans=-1
def MAX(a,b):
  return max(a,b) 
STST=SegTree(MAX,-10**18,N)
for i in range(N):
  STST.set(i,Q[i][0])
#print(Q)
for i in range(N):
  if i in check:
    continue
  ans+=1
  now=Q[i][1]
  check.add(i)
  while now<=maxr:
    ng=i
    ok=N-1
    while abs(ok-ng)>1:
      m=(ok+ng)//2
      #print(ok,ng)
      #print(i,m,STST.prod(i,m+1))
      if STST.prod(i,m+1)>=now:
        ok=m
        #print(m)
      else:
        ng=m
    check.add(ok)
    STST.set(ok,-10**18)
    now=Q[ok][1]
    #print(i,ok)
print(ans)