Was a Mexican employee of M0 , M1 , M2 , and M3 employed by M4 and M5 and employed by M6
SELECT count(*) WHERE {
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M0 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M1 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M2 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M3 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M4 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M5 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M6 .
?x0 ns:people.person.nationality ns:m.0b90_r
}