At this point, there are several things you can do.  If your string was mistyped, use @key{DEL} to cancel a previous input item (@pxref{Basic Isearch}), <del>@kbd{C-M-w}</del> <ins>@kbd{C-M-d}</ins> to erase one character at a time, or @kbd{M-e} to edit it.  If you like the place you have found, you can type @key{RET} to remain there.  Or you can type @kbd{C-g}, which removes from the search string the characters that could not be found (the @samp{T} in @samp{FOOT}), leaving those that were found (the @samp{FOO} in @samp{FOOT}).  A second @kbd{C-g} at that point cancels the search entirely, returning point to where it was when the search started.