program punch(input,output);
var
 a:array[1..10000,1..2]of longint;
 b:array[1..10000]of boolean;
 n,i,j,s:integer;
begin
 assign(input,'punch.in');assign(output,'punch.out');
 reset(input);rewrite(output);
 readln(n);
 s:=0;
 for i:=1 to n do begin
  readln(a[i,1],a[i,2]);
  for j:=1 to i-1 do
   if b[j] then begin
    if (a[i,1]<a[j,1])and(a[i,2]>a[j,1])and(a[i,2]<a[j,2])then a[j,1]:=a[i,2];
    if (a[i,2]>a[j,2])and(a[i,1]>a[j,1])and(a[i,1]<a[j,2])then a[j,2]:=a[i,1];
    if (a[i,1]<=a[j,1])and(a[i,2]>=a[j,2])then begin b[j]:=false;dec(s);end;
   end;
  b[i]:=true;
  inc(s);
 end;
 write(s);
 close(input);close(output);
end.