(global-set-key (kbd "M-S-n") 'f1) do not define key binding, but
(global-set-key (kbd "M-n") 'f2) do for both M-n and M-N.
In my research I found that C-h k M-M take line
M-k (_translated_ from M-K) runs the command kill-sentence
while C-h k M-m
M-m runs the command back-to-indentation.
