var n,p,i,k:longint;
    f,g:text;
function ver(x:longint):longint;
var nr:longint;
begin
nr:=0;
while x mod 5=0 do
      begin
      x :=x div 5;
      inc(nr);
      end;
ver:=nr;
end;
begin
assign(f,'fact.in');reset(f);
assign(g,'fact.out');rewrite(g);
readln(f,p);
k:=0;
n:=p*5;
for i:=1 to n do
    begin
    if i mod 5=0 then k:=k+ver(i);
    if k=p then
       begin
       write(g,i);
       break;
       end;
    end;
if p=0 then write(g,'1');
if (p<0)or(p>100000000) then write(g,'-1');
close(f);close(G);
end.