program t482;

{$APPTYPE CONSOLE}
var n,i:integer;
a:array[0..30] of int64;
f1,f2:text;
begin
assign(f1,'input.txt');
assign(f2,'output.txt');
reset(f1);
rewrite(f2);
repeat
readln(f1,n);
a[0]:=1; a[1]:=1;a[2]:=1;
for i:=3 to n do begin
a[i]:=a[i-1]+a[i-2];
a[i-2]:=a[i-1];
a[i]:=a[i-1];
end;
if n<> -1 then writeln(f2,a[n]);
until n=-1;
close(f2);
close(f1);
end.