Was M1 employed by M2 , employed by M3 , and employed by a country of nationality of M0
SELECT count(*) WHERE {
?x0 ^ns:people.person.nationality M0 .
M1 ns:people.person.employment_history/ns:business.employment_tenure.company ?x0 .
M1 ns:people.person.employment_history/ns:business.employment_tenure.company M2 .
M1 ns:people.person.employment_history/ns:business.employment_tenure.company M3
}