program Fact;
var n,s :longint;
var f,ff :text;
begin
assign(f,'fact.in');
reset(f);
readln(f,n);
close(f);
s:=-1;
if n=0 then
s:=1;
if(n>0) and((n*5 mod 5)=0) then
s:=n*5;
assign(ff,'fact.out');
rewrite(ff);
write(ff,s);
close(ff)
end.