uses crt;
var n:longint;
{------------------------chuong-trinh-con-------------------------}
function tim(n:longint):longint;
begin
if n=1 then tim:=1
else tim:=tim(n-1)+tim(n-1);
end;
{------------------------chuong-trinh-chinh-----------------------}
begin
clrscr;
write('nhap n='); readln(n);
writeln(tim(n));
readln;
end.