program Nunta;
var
   Fl : text;
   a : array[1..999] of longint;
   i, j, k, i1, i2, n : longint;
begin
   Assign(Fl,'nunta.in');
   Reset(Fl);
   ReadLn(Fl,n);
   Close(Fl);

   a[1] := 1;
   a[2] := 1;
   for i := 3 to n+1 do
      a[i] := a[i-2] + a[i-1];

   Assign(Fl,'nunta.out');
   rewrite(Fl);
   writeln(Fl,a[n+1]);
   Close(fl);
end.