instruction: calculate how many times patient 56635 has received cont inv mec ven <96 hrs procedures.
response: SELECT COUNT(*) FROM procedures_icd WHERE procedures_icd.icd9_code = (SELECT d_icd_procedures.icd9_code FROM d_icd_procedures WHERE d_icd_procedures.short_title = 'cont inv mec ven <96 hrs') AND procedures_icd.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 56635)