uses crt;

var f,g:text;
	p,n:longint;
function zero(n:longint):longint;
var nr5:longint;

begin
	nr5:=0;
	while n<> 0 do 
		begin
			nr5:= nr5+ n div 5;
			n:=n div 5;
		end;
	zero:=nr5;
end;
	 
function caut(p:longint):longint;
var pas,lim:longint;

begin
	pas:=1<<30;
	lim:=0;
	while pas <> 0 do 
		begin
			if zero(lim+pas)<p then 
				lim:=lim+pas;
			pas:=pas>>1;
		end;
	caut := 1 + lim
end;
begin
	assign(f,'fact.in');
	reset(f);
	assign(g,'fact.out');
	rewrite(g);
	readln(f,p);
	n:=caut(p);
	if zero(n)=p then writeln(g,n)
		else writeln(g,-1);
	close(f);
	close(g);
	
end.