A unary minus is a minus sign that precedes an operand but does not follow one.
A binary minus sign is one that is sandwiched between two operands.
So that in -3, the minus sign preceding the "3" is a unary minus, whereas,
in 5-3, the minus sign is a binary one. Alter project #1 so that your
converter recognizes a unary minus that starts an expression and one that
immediately follows a left parenthesis, as in -3*(-4 +8).