consulta mismo DGMkey

for $anun in input()/anuncio
let $key := $anun/DGMkey
where count(for $b in input()/anuncio where $b/DGMkey = $key return $anun/DGMkey)>1
return

{ $key , count(for $b in input()/anuncio where $b/DGMkey = $key return $anun/DGMkey)}