Was M2 a person whose country of nationality employed M0 and M1
SELECT count(*) WHERE {
?x0 ns:business.employer.employees/ns:business.employment_tenure.person M0 .
?x0 ns:business.employer.employees/ns:business.employment_tenure.person M1 .
M2 a ns:people.person .
M2 ns:people.person.nationality ?x0
}