program nunta;
var f,g:Text;
    n,i,la,lb,lc,j,t:longint;
    a,b,c:array[1..100000]of byte;
begin
assign(f,'nunta.in');
assign(g,'nunta.out');
reset(f);
rewrite(g);
read(f,n);
la:=1;
lb:=1;
a[1]:=1;
b[1]:=1;
for i:=2 to n do
  begin
    for j:=1 to lb do c[j]:=b[j];
    lc:=lb;
    t:=0;
    for j:=1 to lb do
      begin
        b[j]:=b[j]+a[j]+t;
        t:=b[j] div 10;
        b[j]:=b[j] mod 10;
      end;
    if (t>0)then
      begin
        inc(lb);
        b[lb]:=t;
      end;
    la:=lc;
    for j:=1 to la do a[j]:=c[j];
  end;
for i:=lb downto 1 do write(g,b[i]);
close(f);
close(g);
end.