var f:text;
    p,r,fac,facc,dif:longint;

begin
assign(f ,'fact.in');
reset(f);
read(f,p);
close(f);
r:=0;
fac:=1;
while r<p do
 begin
  r:=r+fac;
  fac:=fac*5;
 end;
assign(f ,'fact.out');
rewrite(f);
if r=p then
write(f,fac)
 else
if (r-p)mod 5<>0 then write(f,'-1')
else
 begin
 dif:=(r-p)*5;
 facc:=fac div dif;
 write(f,facc);
 end;
close(f);
end.