function cate_0_n(n:longint):longint;
 var i,p,aux:longint;
     sw:boolean;
 begin
 p:=0;
 for i:=1 to n do
  begin
  aux:=i;
  sw:=true;
  while (aux<>0) and (sw) do
  if aux mod 5=0 then begin
                      p:=p+1;
                      aux:=aux div 5;
                      sw:=true;
                      end
                 else sw:=false;
  end;
 cate_0_n:=p;
 end;
var n,p,x:longint;
    f:text;
    sw:boolean;
begin
assign(f,'fact.in');
reset(f);
read(f,p);
close(f);
assign(f,'fact.out');
rewrite(f);
sw:=true;
for n:=1 to maxlongint do
if cate_0_n(n)=p then begin
                       x:=n;
                       sw:=false;
                       end;
if sw then write(f,'-1')
      else write(f,x);
close(f);
end.