var p,n,zero,j:longint;

begin

assign(input,'fact.in'); reset(input);
readln(p);
repeat
  begin
    n:=n+1;
    j:=n;
    while j mod 5 = 0 do
      begin
        zero:=zero+1;
        j:=j div 5;
      end;

  end;
until zero>=p;

assign(output,'fact.out');  rewrite(output);
if zero=p then writeln(n)
  else writeln('-1');
close(output);
end.