program fact;
var f : text;
    p, n, k, x, l : longint;
begin
assign (f, 'fact.in');
reset (f);
read (f, p);
close (f);
k:=0;
l:=0;
assign (f, 'fact.out');
rewrite (f);
if p>0 then
repeat
 k:=k+5;
 inc (l);
 if (k mod 10<>0) and (k mod 5=0) then begin
                                        x:=k div 5;
                                        while (x mod 5=0) and (l<p) do begin
                                                                        inc (l);
                                                                        x:=x div 5;
                                                                       end;
                                       end;
until l=p;
if p=0 then write (f, 1)
       else if p<0 then write (f, -1)
                   else write (f, k);
close (f);
end.