var  f,g:text; p,i,min,d,c,aux:longint;
begin
assign(f,'fact.in'); reset(f);
read(f,p); close(f);
i:=0;
if p=0 then
begin
assign(g,'fact.out'); rewrite(g);
write(g,1);close(g); exit;
end;
while c<p do
begin
     i:=i+5;aux:=i;
     while aux mod 5=0 do
     begin
     aux:=aux div 5;
     inc(c);
     end;
end;
assign(g,'fact.out'); rewrite(g);
if c=p then
write(g,i)
else
write(g,'-1');
close(g);
end.