Batters

AtCoder

IDabc256_b

Time2000ms

Memory256MB

Difficulty—

> Takahashi is trying to create a game inspired by baseball, but he is having difficulty writing the code. > Write a program for Takahashi that solves the following problem. There are $4$ squares called Square $0$, Square $1$, Square $2$, and Square $3$. Initially, all squares are empty. There is also an integer $P$; initially, $P = 0$. Given a sequence of positive integers $A = (A_1, A_2, \dots, A_N)$, perform the following operations for $i = 1, 2, \dots, N$ in this order: 1. Put a piece on Square $0$. 2. Advance every piece on the squares $A_i$ squares ahead. In other words, if Square $x$ has a piece, move the piece to Square $(x + A_i)$. If, however, the destination square does not exist (i.e. $x + A_i$ is greater than or equal to $4$) for a piece, remove it. Add to $P$ the number of pieces that have been removed. Print the value of $P$ after all the operations have been performed. ## Constraints * $1 \leq N \leq 100$ * $1 \leq A_i \leq 4$ * All values in input are integers. ## Input Input is given from Standard Input in the following format: $N$ $A_1$ $A_2$ $\dots$ $A_N$ [samples]

Samples

Input #1

4
1 1 3 2

Output #1

3

The operations are described below. After all the operations have been performed, $P$ equals $3$.

*   The operations for $i=1$:
    1.  Put a piece on Square $0$. Now, Square $0$ has a piece.
    2.  Advance every piece on the squares $1$ square ahead. After these moves, Square $1$ has a piece.
*   The operations for $i=2$:
    1.  Put a piece on Square $0$. Now, Squares $0$ and $1$ have a piece.
    2.  Advance every piece on the squares $1$ square ahead. After these moves, Squares $1$ and $2$ have a piece.
*   The operations for $i=3$:
    1.  Put a piece on Square $0$. Now, Squares $0$, $1$, and $2$ have a piece.
    2.  Advance every piece on the squares $3$ squares ahead.  
        Here, for the pieces on Squares $1$ and $2$, the destination squares do not exist (since $1+3=4$ and $2+3=5$), so remove these pieces and add $2$ to $P$. $P$ now equals $2$. After these moves, Square $3$ has a piece.
*   The operations for $i=4$:
    1.  Put a piece on Square $0$. Now, Squares $0$ and $3$ have a piece.
    2.  Advance every piece on the squares $2$ squares ahead.  
        Here, for the piece on Square $3$, the destination square does not exist (since $3+2=5$), so remove this piece and add $1$ to $P$. $P$ now equals $3$.  
        After these moves, Square $2$ has a piece.

Input #2

3
1 1 1

Output #2

0

The value of $P$ may not be updated by the operations.

Input #3

10
2 2 4 1 1 1 4 2 2 1

Output #3

API Response (JSON)

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  "problem": {
    "name": "Batters",
    "description": {
      "content": "> Takahashi is trying to create a game inspired by baseball, but he is having difficulty writing the code.   > Write a program for Takahashi that solves the following problem. There are $4$ squares c",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc256_b"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "> Takahashi is trying to create a game inspired by baseball, but he is having difficulty writing the code.  \n> Write a program for Takahashi that solves the following problem.\n\nThere are $4$ squares c...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

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