Temporary variable required in SSA

Question

Consider the following code segment:

c = b + a

e = c - a

f  = c * e

h = c + a

i = h + f

The minimum number of temporary variable required to convert the above code segment to static single assignment form is ________.

Comments

same in question 2nd equation is simply store b , which can be seen via DAG , and we can save 1 temp register.

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@ Anu007  Agree with 4 temporary variables for this segment.
But
If question asks :  The minimum number of temporary variable required to convert the above "part of program" to static single assignment form is :
Answer would be same "4" or "5"?

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It's already in SSA form. So 0 temporary variables required.