题目描述
Problem Statement
You have an empty sequence and N balls. The size of the $i-th ball (1 \leq i \leq N)$ is 2^{A_i}.
You will perform N operations.
In the i-th operation, you add the i-th ball to the right end of the sequence, and repeat the following steps:
- If the sequence has one or fewer balls, end the operation.
- If the rightmost ball and the second rightmost ball in the sequence have different sizes, end the operation.
- If the rightmost ball and the second rightmost ball in the sequence have the same size, remove these two balls and add a new ball to the right end of the sequence with a size equal to the sum of the sizes of the two removed balls. Then, go back to step 1 and repeat the process.
Determine the number of balls remaining in the sequence after the N operations.
Input
The input is given from Standard Input in the following format:
N
$A_1 A_2 \ldots A_N$
Output
Print the number of balls in the sequence after the N operations.
Constraints
- $1 \leq N \leq 2 \times 10^5$
- $0 \leq A_i \leq 10^9$
- All input values are integers.
Sample Input 1
7
2 1 1 3 5 3 3
Sample Output 1
3
The operations proceed as follows:
- After the first operation, the sequence has one ball, of size 2^2.
- After the second operation, the sequence has two balls, of sizes 2^2 and 2^1 in order.
- After the third operation, the sequence has one ball, of size 2^3. This is obtained as follows:
- When the third ball is added during the third operation, the sequence has balls of sizes 2^2, 2^1, 2^1 in order.
- The first and second balls from the right have the same size, so these balls are removed, and a ball of size 2^1 + 2^1 = 2^2 is added. Now, the sequence has balls of sizes 2^2, 2^2.
-
Again, the first and second balls from the right have the same size, so these balls are removed, and a ball of size 2^2 + 2^2 = 2^3 is added, leaving the sequence with a ball of size 2^3.
-
After the fourth operation, the sequence has one ball, of size 2^4.
- After the fifth operation, the sequence has two balls, of sizes 2^4 and 2^5 in order.
- After the sixth operation, the sequence has three balls, of sizes 2^4, 2^5, 2^3 in order.
- After the seventh operation, the sequence has three balls, of sizes 2^4, 2^5, 2^4 in order.
Therefore, you should print 3, the final number of balls in the sequence.
Sample Input 2
5
0 0 0 1 2
Sample Output 2
4
The operations proceed as follows:
- After the first operation, the sequence has one ball, of size 2^0.
- After the second operation, the sequence has one ball, of size 2^1.
- After the third operation, the sequence has two balls, of sizes 2^1 and 2^0 in order.
- After the fourth operation, the sequence has three balls, of sizes 2^1, 2^0, 2^1 in order.
- After the fifth operation, the sequence has four balls, of sizes 2^1, 2^0, 2^1, 2^2 in order.
Therefore, you should print 4, the final number of balls in the sequence.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分