Figure 1

Enter infix: a + b
   postfix: ab+
Enter infix: (((((a + b)))))
   postfix: ab+
Enter infix: c - d * e + f
   postfix: cde*-f+
Enter infix: c - d * (e + f)
   postfix: cdef+*-
Enter infix: (c - d * e) + f
   postfix: cde*-f+
Enter infix: c - (d * (e + f))
   postfix: cdef+*-
Enter infix: (c - d) * e + f
   postfix: cd-e*f+
Enter infix: (c - d) * (e + f)
   postfix: cd-ef+*
Enter infix: (((a - b) / (c + d)) * e)
   postfix: ab-cd+/e*