Mahjong 2

题目描述

You have $3M - 1$ cards, each labeled with an integer from $1$ to $N$. For every $i$ with $1 \le i \le N$, there are $A_i$ cards labeled $i$.

Choose an integer $K$ with $1 \le K \le N$ and add one additional card labeled $K$. Your goal is to make the following condition true.

Condition: You can repeat the operation below exactly $M$ times and remove all cards.

• In one operation, remove either
  • three cards with the same label, or
  • three cards whose labels are consecutive integers.

List all values of $K$ for which the condition can be satisfied.

输入格式

The first line contains two integers $N$ and $M$ ($1 \le N \le 5 \cdot 10^5$, $1 \le M \le 10^8$).

The second line contains integers $A_1, A_2, \ldots, A_N$ ($0 \le A_i$, $\sum_{i=1}^{N} A_i = 3M - 1$).

输出格式

On the first line, output $L$, the number of values of $K$ that satisfy the condition.

On the second line, output all such values of $K$ in increasing order.

样例输入 #1

5 4
0 4 2 2 3

样例输出 #1

2
2 5

样例输入 #2

4 1
1 0 0 1

样例输出 #2

0

样例输入 #3

8 15
7 10 4 2 8 6 3 4

样例输出 #3

3
1 4 7