Black and White Landscaper

Mina is a landscaper known for decorating gardens with Even trees. A tree is a simple connected graph without cycles. A tree is Even if it satisfies the following conditions.

• It has one root vertex. Two vertices connected by an edge have a parent-child relationship, and the one closer to the root is the parent.
• Every vertex is painted either white or black.
  • A vertex with no children may be any color.
  • A vertex with children must have the color that is more common among all descendants of that vertex. That is, it must be white if there are more white descendants, and black if there are more black descendants. If the numbers of white and black descendants are equal, it may be any color. Here, for two distinct vertices $a$ and $b$, $b$ is an ancestor of $a$ if $b$ lies on the simple path from $a$ to the root vertex, and then $a$ is a descendant of $b$.

Mina took a tree with $N$ vertices to decorate the HCPC contest venue. When she arrived, however, she forgot which vertex was the root. Depending on which vertex is chosen as the root, the tree may or may not be Even. Find every vertex that makes the tree Even when it is chosen as the root.

The first line contains the number of vertices $N$. ($2 \le N \le 200000$)

The second line contains $N$ integers $C_1, C_2, \cdots, C_N$ separated by spaces. If vertex $i$ is white, $C_i=0$. If it is black, $C_i=1$.

Each of the next $N-1$ lines contains two vertex numbers $u$ and $v$ separated by a space, meaning that an edge connects them. ($1 \le u,v \le N$; $u \ne v$)

On the first line, print the number of vertices that satisfy the condition.

On the second line, print the numbers of all vertices that satisfy the condition in ascending order, separated by spaces.

If no vertex satisfies the condition, do not print the second line.