instruction: how many patients whose marital status is widowed and diagnoses long title is benign neoplasm of spinal meninges?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id WHERE demographic.marital_status = "WIDOWED" AND diagnoses.long_title = "Benign neoplasm of spinal meninges"