How to write a code for the decision variables X and S with 4 Indices in Cplex to run a linear programming problem

This nurses' timetabling problem can be modeled as a mixed integer program with four decisions variables: - xkv=1 if nurse i,i=1,,n, works on shift t,t=1,2,3. of day j,j=1,.7, of week w,w=1,.nw, and 0 otherwise; - yi==1 if nurse i,i=1,,n, has a night shift during week w,w=1,,nw, and 0 otherwise; - djw=1 if nurse i,i=1,,n, has day j,j=1,,7, off during week w,w=1,,nw, and 0 otherwise; and - sgrw is the number of outsourced nurses of gender g,g=0 for male and g=1 for female, during shift t,t=1,2,3, of day j.j=1,,7, of week w,w=1,,nw