Codeforces Round #245 (Div. 1)——Xor-tree

const int MAXN = 110000;

VI G[MAXN], ans;
int now[MAXN], goal[MAXN];

void dfs(int u, int fa, int a, int b)
{
	int rev = ((now[u] ^ a) != goal[u]);
	if (rev) 
	{
		ans.push_back(u);
		a ^= 1;
	}
	REP(i, G[u].size())
	{
		int v = G[u][i];
		if (v != fa)
			dfs(v, u, b, a);
	}
}

int main()
{
	//    freopen("in.txt", "r", stdin);
	int n, a, b;
	while (~RI(n))
	{
		FE(i, 0, n) G[i].clear();
		ans.clear();

		REP(i, n - 1)
		{
			RII(a, b);
			G[a].push_back(b);
			G[b].push_back(a);
		}
		FE(i, 1, n) RI(now[i]);
		FE(i, 1, n) RI(goal[i]);
		dfs(1, 0, 0, 0);
		WI(ans.size());
		REP(i, ans.size())
			WI(ans[i]);
	}
	return 0;
}