Expression Evaluation

INPUT FILE: eval.in
OUTPUT FILE: eval.out

Often many expressions in regular mathematical notation such as 5 * (4 + 3) involve one or more sets of parentheses which make evaluation difficult. However, when we express a mathematical expression as a binary tree parentheses are not needed. For this example,

  *

 / \
5   +
   / \
  4   3

We cannot multiply the 5 without first evaluating 4 + 3.
Your task is to evaluate such an expression given the entries in the binary tree.

INPUT
The input file contains 5 data sets.
The first line of the data gives the number of rows 1<=N<=10 in the binary tree.
The next N lines each contain the elements of the tree, level-by-level from left to right. Each element will be either an operator (*, +, - and / (integer division, guaranteed to never cause you to divide by zero)) or a number from 1 to 9. It is guaranteed that the given tree constitutes a legal expression (operators have 2 children, numbers have none). Furthermore, it is guaranteed that evaluating any subtree of the given tree will result in an integer between -32000 and 32000.

OUTPUT
Give the number to which each input evaluates.

Sample Input File

3
*
5 +
4 3
2
/
5 3

(and 3 more inputs)

Output for Sample Input

35
1