Governor#2277
In a distant town, a new governor recently took office. He disliked speed racers so much that his first order was to increase fines for speeding. This angered the residents, so the governor decided to leave town for a while to give people time to calm down and forgive him.
The governor plans to travel across the country to visit an old friend who is also a governor in another distant town. Since air travel is unreliable and subject to attacks, he decided to use the existing railway network that connects all towns in the country.
Since visiting any town more than once during his trip there and back is quite boring, he wants to avoid revisiting towns as much as possible. Please help him determine which towns he will necessarily have to visit more than once, regardless of which round-trip route he chooses.
The first line contains two integers and — the total number of towns in the railway network and the total number of lines between the towns, respectively (2 \leq N \leq 10000, 1 \leq K \leq 200000). Each town is assigned a serial number from to . Each of the next lines describes an existing railway line, giving the serial numbers of towns A_i and B_i that the line connects. Two towns may be connected by several railway lines. Each railway line is bidirectional. The last line contains two integers and (1 \leq S \leq E \leq N) — the serial numbers of the governor's town and his friend's town, respectively.
On the first line, output a single integer — the number of towns that the governor must visit more than once (excluding towns and ). The following lines should contain the serial numbers of these towns in increasing order.
Example 1