$/=$%=<>;
$_=<>;
@a=('!',A..Z,a..j);
s/\./!/;
($a,$b)=@a[$i,$i+1],
s/\.(.{$%})?!|!(.{$%})?\./!$1$2!/s||
s/$a(.{$%})?#/$a$1$b/s|s/#(.{$%})?$a/$b$1$a/s||
$i++until/\w(.{$%})?\.|\.(.{$%})?\w/s;
print$i+1