Did M3 star a person that M1 and M2 influenced
SELECT count(*) WHERE {
?x0 a ns:people.person .
?x0 ns:influence.influence_node.influenced_by M1 .
?x0 ns:influence.influence_node.influenced_by M2 .
M3 ns:film.film.starring/ns:film.performance.actor ?x0
}