How would you determine the number of missing or nonmissing values in computations? | SAS Programming

To determine the number of missing values that are excluded in a computation, use the NMISS function.
Program:
data _null_;
m = . ;
y = 4 ;
z = 0 ;
N = N(m , y, z);
NMISS = NMISS (m , y, z);
run;
The above program results in N = 2 (Number of non missing values) and NMISS = 1 (number of missing values).