program ex;
type
 ss=array[1..10000]of longint;
 sz=array[0..10000]of boolean;
var
 f1,f2:text;
 a,b:ss;
 c,d:sz;
 n,t:integer;
procedure init;
 var
  i,j,k:integer;
 begin
  assign(f1,'punch.in');
  assign(f2,'punch.out');
  reset(f1);
  rewrite(f2);
  readln(f1,n);
  t:=n;i:=0;k:=0;
  while not eof(f1) do
   begin
    inc(i);
    readln(f1,a[i],b[i]);
    if (c[a[i]]=false)and(d[b[i]]=false) then
      begin
       c[a[i]]:=true;
       d[b[i]]:=true;
      end
      else if (c[a[i]]=true)and(d[b[i]]=true) then
          begin
           dec(i);
           dec(t);
          end;
    k:=i;
    for j:=1 to k-1 do
      if (a[k]<=a[j])and(b[k]>=b[j]) then
       begin
        c[a[j]]:=false;
        d[b[j]]:=false;
        a[j]:=a[i];
        b[j]:=b[i];
        dec(i);
        dec(t);
       end;
   end;
  writeln(f2,t)
 end;
begin
 init;
 close(f2);
end.