program alex;
var f:text;
    a,b,c:array[1..10000]of integer;
    n,v,t,i,k,d:longint;
begin
assign(f,'nunta.in');reset(f);
readln(f,n);
close(f);
assign(f,'nunta.out');rewrite(f);
if n<4 then begin
            case n of
            1:writeln(f,n);
            2:writeln(f,n);
            3:writeln(f,n);
            end;
            end
       else begin
            v:=1;
            a[1]:=1;
            t:=1;
            b[1]:=1;
            d:=2;
            while d<=n do
                  begin
                  d:=0;
                  k:=0;
                  for i:=1 to t do
                      begin
                      k:=k+1;
                      c[k]:=(a[i]+b[i]+d)div 10;
                      d:=(a[i]+b[i]+d)mod 10;
                      end;
                  if d<>0 then begin
                               k:=k+1;
                               c[k]:=d;
                               end;
                  v:=t;
                  for i:=1 to v do
                      a[i]:=b[i];
                  t:=k;
                  for i:=1 to k do
                      b[i]:=c[i];
                  d:=d+1;
                  end;
            for i:=k downto k do
                write(f,b[i]);
            end;
close(f);
end.