Dispute

题意：有 $n$ 个计数器和 $m$ 条电线，每个计数器都对应着一个额定值 $a_i$ ，初始时所有计数器的值均为 $0$ ,现在你可以按若干个计数器上的按钮，每次按按钮可以使该计数器以及与该计数器通过电线相连的计数器的值都 $+1$ ，每个计数器最多只能按一次。当你进行这样的操作若干次后，若有一个计数器上的值与该计数器的额定值一样，你就失败了。需要输出任意一种方案使你可以获胜。若无法获胜，输出 $-1$。

Valera has $ n $ counters numbered from $ 1 $ to $ n $ . Some of them are connected by wires, and each of the counters has a special button. Initially, all the counters contain number $ 0 $ . When you press a button on a certain counter, the value it has increases by one. Also, the values recorded in all the counters, directly connected to it by a wire, increase by one. Valera and Ignat started having a dispute, the dispute is as follows. Ignat thought of a sequence of $ n $ integers $ a_{1},a_{2},...,a_{n} $ . Valera should choose some set of distinct counters and press buttons on each of them exactly once (on other counters the buttons won't be pressed). If after that there is a counter with the number $ i $ , which has value $ a_{i} $ , then Valera loses the dispute, otherwise he wins the dispute. Help Valera to determine on which counters he needs to press a button to win the dispute.

The first line contains two space-separated integers $ n $ and $ m $ $ (1<=n,m<=10^{5}) $ , that denote the number of counters Valera has and the number of pairs of counters connected by wires. Each of the following $ m $ lines contains two space-separated integers $ u_{i} $ and $ v_{i} $ $ (1<=u_{i},v_{i}<=n,u_{i}≠v_{i}) $ , that mean that counters with numbers $ u_{i} $ and $ v_{i} $ are connected by a wire. It is guaranteed that each pair of connected counters occurs exactly once in the input. The last line contains $ n $ space-separated integers $ a_{1},a_{2},...,a_{n} $ $ (0<=a_{i}<=10^{5}) $ , where $ a_{i} $ is the value that Ignat choose for the $ i $ -th counter.

If Valera can't win the dispute print in the first line -1. Otherwise, print in the first line integer $ k $ $ (0<=k<=n) $ . In the second line print $ k $ distinct space-separated integers — the numbers of the counters, where Valera should push buttons to win the dispute, in arbitrary order. If there exists multiple answers, you are allowed to print any of them.

5 5
2 3
4 1
1 5
5 3
2 1
1 1 2 0 2

2
1 2

4 2
1 2
3 4
0 0 0 0

3
1 3 4