There are $N$ people labeled $1$ to $N$, who have played several one-on-one games without draws. Initially, each person started with $0$ points. In each game, the winner's score increased by $1$ and the loser's score decreased by $1$ (scores can become negative). Determine the final score of person $N$ if the final score of person $i\ (1\leq i\leq N-1)$ is $A_i$. It can be shown that the final score of person $N$ is uniquely determined regardless of the sequence of games.

The input is given from Standard Input in the following format:

```
$N$
$A_1$ $A_2$ $\ldots$ $A_{N-1}$
```

Print the answer.

-   $2 \leq N \leq 100$
-   $-100 \leq A_i \leq 100$
-   All input values are integers.

2

Here is one possible sequence of games where the final scores of persons 1,2,3 are 1, -2, -1, respectively.

• Initially, persons 1,2,3,4 have 0,0,0,00,0,0,0 points, respectively.
• Persons 1 and 2 play, and person 1 wins. The players now have 1,-1,0,0 point(s).
• Persons 1 and 4 play, and person 4 wins. The players now have 0,-1,0,1 point(s).
• Persons 1 and 2 play, and person 1 wins. The players now have 1,-2,0,1 point(s).
• Persons 2 and 3 play, and person 2 wins. The players now have 1,-1,-1,1 point(s).
• Persons 2 and 4 play, and person 4 wins. The players now have 1,-2,-1,2 point(s).

In this case, the final score of person 4 is 2. Other possible sequences of games exist, but the score of person 4 will always be 2 regardless of the progression.