type tip=array [1..300] of byte;
const max=300;

var a,b,c:array [1..300] of byte;
    i,lim,m,k,n:integer;
    f,g:text;

procedure aduna(var a,b,c:tip);
  var t,s,j:integer;
begin
  t:=0;
  s:=0;
  for j:=max downto lim do
    begin
      s:=a[j]+b[j]+t;
      c[j]:=s mod 10;
      t:=s div 10;
    end;
  if t<>0 then
    begin
      dec(lim);
      c[lim]:=t;
    end;
end;

begin
  assign(f,'nunta.in');
  assign(g,'nunta.out');
  reset(f);
  rewrite(g);
  readln(f,n);
  a[max]:=1;
  b[max]:=1;
  lim:=max;
  repeat
    inc(m);
    if m mod 3=1 then
      aduna(a,b,c)
    else
      if m mod 3=2 then
        aduna(b,c,a)
      else
        aduna(a,c,b);
  until m>=n-1;
  if n=1 then
    write(g,'1')
  else
    if m mod 3=1 then
      for i:=lim to max do
        write(g,c[i])
    else
      if m mod 3=2 then
        for i:=lim to max do
          write(g,a[i])
      else
        for i:=lim to max do
          write(g,b[i]);
  close(g);
end.