first, you're reading in the filehandle in scalar context, which only reads one line in.
to get the whole file into $lines, you have to set $/ to undef (see perlvar), like:

my $lines = do {
  local $/; # sets $/ locally to undef;
  <FILE>;
};
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second, then you split the whole file into an array; this could be done easier by reading in in list context: my @array = <FILE>;