//na                            :cuixiaofei;
//da                            :08_11_13;
program punch;
  type
    sss                         =record
                              z,y:longint;
                                end;
  var
    n,zge,fge                   :longint;
    a                           :array[1..10000,1..2] of longint;
    f                           :array[1..10000] of sss;
    f1,f2                       :text;
  procedure swap(var x,y:longint);
    var
      t                         :longint;
  begin
    t:=x;
    x:=y;
    y:=t;
  end;
  procedure init;
    var
     i                          :longint;
  begin
    assign(f1,'punch.in');
    reset(f1);
    assign(f2,'punch.out');
    rewrite(f2);
    readln(f1,n);
    fge:=0;
    zge:=0;
    for i:=1 to n do
      begin
        readln(f1,a[i,1],a[i,2]);
        if a[i,1]>a[i,2] then
          swap(a[i,1],a[i,2]);
      end;
  end;
  procedure zhenghe(k:longint);
    var
      i                         :longint;
  begin
    for i:=1 to k-1 do
      begin
        if f[i].y>f[k].z then
          begin
            f[i].y:=f[k].y;
            f[k].z:=f[i].z;
          end
        else if f[i].z<f[k].y then
          begin
            f[i].z:=f[k].z;
            f[k].y:=f[i].y;
          end;
      end;
  end;
  procedure chakan(k:longint);
    var
      i                         :longint;
  begin
    for i:=1 to fge do
      if (a[k,1]>f[i].z) and (a[k,2]<f[i].y) then
        exit;
    for i:=1 to fge do
          begin
            if (a[k,1]<f[i].z) and (a[k,2]>f[i].z) and (a[k,2]<f[i].y) then
              begin
                inc(zge);
                f[i].z:=a[k,1];
                zhenghe(i);
                exit;
              end
            else if (a[k,1]>f[i].z) and (a[k,1]<f[i].y) and (a[k,2]>f[i].y) then
              begin
                inc(zge);
                f[i].y:=a[k,2];
                zhenghe(i);
                exit;
              end
            else if (a[i,1]<f[i].z) and (a[i,2]>f[i].y) then
              begin
                f[i].z:=a[i,1];
                f[i].y:=a[i,2];
                zhenghe(i);
                inc(zge);
                exit;
              end;
          end;
    inc(fge);
    inc(zge);
    f[fge].z:=a[k,1];
    f[fge].y:=a[k,2];
  end;
  procedure main;
    var
      i,j                       :longint;
  begin
    for i:=n downto 1 do
      begin
        chakan(i);
      end;
  end;
  procedure print;
  begin
    writeln(f2,zge);
    close(f1);
    close(f2);
  end;
  begin
    init;
    main;
    print;
  end.