var f,g:text;
p,a,x:longint;
function nr(q:longint):longint;
begin
        nr:=0;
        while q mod 5=0 do begin
                q:=q div 5;
                nr:=nr+1; end;
end;

begin
        assign (f,'fact.in');assign (g,'fact.out');
        reset(f);rewrite(g);
        read (f,p);
        if p=0 then
                write (g,1)
        else  begin
        a:=0; x:=0;
        while a<p do begin
            x:=x+5;
            a:=a+nr(x);end;
        if a=p then
                write (g,x)
        else
                write (g,-1);end;
        close (g);

end.