var
f,g:text;
r,i,n,j,k1,k2,p:integer;
ant,act,c:array[1..1000]of 0..9;
begin
assign(f,'nunta.in');
reset(f);
readln(f,n);
close(f);
assign(g,'nunta.out');
rewrite(g);
 ant[1]:=1;
 act[1]:=1;
 k1:=1;
 k2:=1;
 for j:=2 to n do
   begin
   k2:=k1;
   for i:=1 to k1 do
      c[i]:=act[i];
    r:=0;
   for i:=1 to k1 do
      begin
      p:=(act[i]+ant[i]+r)div 10;
      act[i]:=(act[i]+ant[i]+r)mod 10;
      r:=p;
      end;
   if r>0 then begin
               k1:=k1+1;
               act[k1]:=r;
               end;
   for i:=1 to k2 do
     ant[i]:=c[i];
   end;
for i:=k1 downto 1 do
write(g,act[i]);
close(g);
end.