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{
  local $/ = undef;
  $contenido = <LIBRO>;
}

$contenido = uc $contenido;
$contenido =~ tr/A-Z/ /cs;

#....
my $contenido;
...
  print LIBROUT join ';', $_, my $f=$PF{$_}, $f/ $npalabras;
  print LIBROUT "\n";
}