program factorial;
var k:longint;
    f,t:text;

function fact(n:longint):int64;
var x,t:int64;
    k,i:longint;
    da:boolean;
begin
  k:=1;da:=false;
  t:=n*n+100000;
  for i:=1 to t do
    begin
      if i mod 5=0 then k:=k+1;
      if i mod 25=0 then n:=n-1;
      if n+1=k then
        begin
          x:=i;
          da:=true;
          break;
        end;
    end;
  if da then fact:=x
        else fact:=-1;
end;

begin
  assign(f,'fact.in');
  reset(f);
  read(f,k);
  close(f);
  {------------------}
  if k=0 then k:=1
         else k:=fact(k);
  {------------------}
  assign(t,'fact.out');
  rewrite(t);
  write(t,k);
  close(t);
end.