program lab25;

var
  i, n: integer;
  f: array [0..100] of integer;

begin
  read(n);

  f[0] := 1;
  f[1] := 1;

  i := 1;
  while f[i] <= n do
  begin
    i := i + 1;
    f[i] := f[i-1] + f[i-2];
  end;

  writeln(f[i]);

  readln;
  readln;
end.