program z3;

{$APPTYPE CONSOLE}

var f1,f2:text;
    a,b,n,i,j,l:longint;
    ma:array [1..200000,1..2] of longint;
    sum:int64;

begin
assign(f1,'task.in');
assign(f2,'task.out');
reset(f1);
readln(f1,n);
for i:=1 to n do
 begin
 readln(f1,ma[i,1],ma[i,2]);
 if ma[i,1]<ma[i,2] then
   begin
    b:=ma[i,1];
    ma[i,1]:=ma[i,2];
    ma[i,2]:=b;
   end;
 end;
close(f1);
rewrite(f2);
a:=0;
for i:=1 to n-1 do
 if ma[i,1]<>0 then
 for j:=i+1 to n do
  begin
  if (ma[j,1]<>0)  then
   if ma[i,1]>ma[j,1] then
    begin

    if ma[i,2]>=ma[j,2] then
     begin
     a:=a+1;
     ma[j,1]:=0;
     ma[j,2]:=0;
     i:=i+2;
     end;
    end else if ma[i,1]<ma[j,1] then
    begin

      if ma[i,2]<=ma[j,2] then
      begin
      a:=a+1;
      ma[i,1]:=0;
      ma[i,2]:=0;
      end;

    end else if ma[i,1]=ma[j,1] then
    begin
    a:=a+1;
    if ma[i,2]<=ma[j,2] then
      begin
      ma[i,1]:=0;
      ma[i,2]:=0;
      end else
      begin
      ma[j,1]:=0;
      ma[j,2]:=0;
      end;
    end;
  end;
writeln(f2,a);  
close(f2);
end.