Problem Statement

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:

• Put a piece on Square 0.
• 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.

Input

Input is given from Standard Input in the following format:
N
$A_1 A_2 \dots A_N$

Output

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.

Sample Input 1

4
1 1 3 2

Sample Output 1

3

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

• The operations for i=1:
• Put a piece on Square 0. Now, Square 0 has a piece.

• Advance every piece on the squares 1 square ahead. After these moves, Square 1 has a piece.

• The operations for i=2:

• Put a piece on Square 0. Now, Squares 0 and 1 have a piece.

• Advance every piece on the squares 1 square ahead. After these moves, Squares 1 and 2 have a piece.

• The operations for i=3:

• Put a piece on Square 0. Now, Squares 0, 1, and 2 have a piece.

• 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:

• Put a piece on Square 0. Now, Squares 0 and 3 have a piece.
• 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.

Sample Input 2

3
1 1 1

Sample Output 2

0

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

Sample Input 3

10
2 2 4 1 1 1 4 2 2 1

Sample Output 3

8

见题面 Input 部分

见题面 Output 部分