#include <bits/stdc++.h>
using namespace std;
const int max_n = 1e5 + 5;
vector<int> g[max_n], path;
bool vis[max_n], x[max_n];
int s;
void dfs(int u) {
  vis[u] = 1;
  x[u] ^= 1;
  path.push_back(u);
  bool leaf = 1;
  for (int v : g[u]) {
    if (!vis[v]) {
      if (!leaf) leaf = 0;
      dfs(v);
      x[u] ^= 1;
      path.push_back(u);
      if (x[v]) {
        x[v] ^= 1;
        path.push_back(v);
        x[u] ^= 1;
        path.push_back(u);
      }
    }
  }
  if (u == s && x[u]) {
    x[u] ^= 1;
    path.pop_back();
  }
}
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  while (m--) {
    int u, v;
    scanf("%d%d", &u, &v);
    g[u].push_back(v);
    g[v].push_back(u);
  }
  s = -1;
  for (int i = 1; i <= n; i++) {
    scanf("%d", &x[i]);
    if (s == -1 && x[i]) s = i;
  }
  if (s != -1) dfs(s);
  bool ok = 1;
  for (int i = 1; i <= n; i++) {
    if (x[i]) {
      ok = 0;
      break;
    }
  }
  if (!ok) {
    puts("-1");
    exit(0);
  }
  int sz = path.size();
  printf("%d\n", sz);
  for (int i = 0; i < sz; i++) {
    if (i != sz - 1)
      printf("%d ", path[i]);
    else
      printf("%d\n", path[i]);
  }
  return 0;
}
