var
	input,output:text;
	n,imp,i,m:int64;
begin
assign(input, 'fact.in'); reset(input);
assign(output, 'fact.out'); rewrite(output);
read(input,n);
close(input);
imp:=0;
i:=0;

if n>0 then
	begin
	
	repeat
	begin
	i:=i+5;
	m:=i;
		while (m mod 5)=0 do
		begin
		imp:=imp+1;
		m:=m div 5;
		end;
	end;
	until (imp=n) or (imp>n);

	if (imp>n) then writeln(output,'-1') else writeln(output,i);	

end
else
writeln(output,'1');

close(output);
end.