Mention the predecessor and the successor of Louis the Pious while being recognized as king of Franks
SELECT ?value1 ?value2 WHERE { wd:Q43974 p:P97 ?s . ?s ps:P97 wd:Q22923081 . ?s pq:P155 ?value1 . ?s pq:P156 ?value2 }
louis the pious: Q43974 king of franks: Q22923081