From the dataset hospdd given by STATA (https://www.stata-press.com/data/r17/hospdd.dta), I want to count the number of observations that satisfy the conditions: month=May and procedure =New.

I gave some tries but they all did not work:

Code:
. sort hospital month

. count if month="May"& procedure = "New"
=exp not allowed
r(101);

. count if month = "May"& procedure = "New"
=exp not allowed
r(101);

. count if (month = "May"& procedure = "New")
month="May" invalid name
r(198);

. count if (month == "May"& procedure = ="New")
type mismatch
r(109);

. count if month == "May"& procedure = ="New"
type mismatch
r(109);

. count if (month == "May") & (procedure =="New")
type mismatch
r(109);

. count if month == "May" & procedure =="New"
type mismatch
r(109);

. count if month == May & procedure == New
May not found
r(111);

. count if month ==May & procedure ==New
May not found
r(111);
Could you please help me to sort it out?

In addition, STATA provide the description for this dataset is that

Code:
A health provider is interested in studying the effect of a new hospital admissions procedure on the satisfaction of patients. The provider has monthly data on patients from January to July. The new admissions procedure was implemented in April by hospitals that were under new management. Of the 46 hospitals in the study, 18 implemented the new procedure.
Could you please help me with the code to list the 18 hospital implemented the new procedure?