refer this- https://gateoverflow.in/227604/static-single-variable
Ans is 7
This can be converted to SSA as
a1 = b + c c1 = a1 + x d1 = b + c1 b1 = a1 + x
a1 = b + c
c1 = a1 + x
d1 = b + c1
b1 = a1 + x
so total count of variables is 7