Problem Statement

You are given an expression in a certain notation consisting of $N$ elements. Output the result of evaluating this expression.

In this notation, an operator is written after its operands. In all other respects, it is the same as the usual infix notation.
Specifically, a b - means $a-b$.
Also, a b + c d + - means $a+b-(c+d)$.

Input

$N$
$A_1\ A_2\ A_3\ ....\ A_N$

$3\le N < 1000$
$N$ is an odd integer
$A_i$ is one of $+$, $-$, or an integer between $1$ and $100$, inclusive
$A$ is valid in the notation of this problem (more specifically, it is guaranteed that among the $A_i$ up to the $i$-th, the number of integers is always greater than the number of elements that are either of $+,-$, and that the total number of integers is exactly $\dfrac{(N+1)}{2}$.)

Output

Output the result of evaluating the given expression, followed by a newline.

Sample

3
75 94 +

169

5
3 3 4 + +

10

5
5 7 - 5 +

3