Professor Octastichs has invented a new programming language, Smeech. An ex
pression in Smeech may be a positive or negative integer, or may be of the form(p e1 e2)where p is a real number between 0 and 1 (inclusive) and e1 and e2 are Smeech expressions. The value represented by a Smeech expression is as follows:
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An integer represents itself
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With probability p,(p e1 e2)represents x+y where x is the value of e1 and y is the value of e2; otherwise it represents x-y.
Given a Smeech expression, what is its expected value?
