var  f,g:text; p,i,min,d,c,aux:longint;
begin
assign(f,'fact.in'); reset(f);
read(f,p); close(f);
i:=1;
if p=0 then
begin
assign(g,'fact.out'); rewrite(g);
write(g,1);close(g); exit;
end;
while min<p do
begin
     inc(i);aux:=i;
     while aux mod 2=0 do
     begin
     aux:=aux div 2;
     inc(d);
     end;
     while aux mod 5=0 do
     begin
     aux:=aux div 5;
     inc(c);
     end;
     if c<d then min:=c
     else
                 min:=d;
end;
assign(g,'fact.out'); rewrite(g);
if min=p then
write(g,i)
else
write(g,'-1');
close(g);
end.