Zero Sum Game

AtCoder

IDabc349_a

Time2000ms

Memory256MB

Difficulty—

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. ## Constraints * $2 \leq N \leq 100$ * $-100 \leq A_i \leq 100$ * All input values are integers. ## Input The input is given from Standard Input in the following format: $N$ $A_1$ $A_2$ $\ldots$ $A_{N-1}$ [samples]

Samples

Input #1

4
1 -2 -1

Output #1

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 $0, 0, 0, 0$ 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.

Input #2

3
0 0

Output #2

Input #3

6
10 20 30 40 50

Output #3

\-150

API Response (JSON)

{
  "problem": {
    "name": "Zero Sum Game",
    "description": {
      "content": "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 t",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc349_a"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "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 t...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

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