question: Which company was acquired by M1 , acquired M6 , and was acquired by M2 , M3 , M4 , and M5
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:business.employer .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M1 .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M2 .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M3 .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M4 .
  ?x0 ns:organization.organization.acquired_by/ns:business.acquisition.acquiring_company M5 .
  ?x0 ns:organization.organization.companies_acquired/ns:business.acquisition.company_acquired M6
  }