#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
const long double eps = 1e-7;
const int inf = 1000000010;
const long long INF = 10000000000010LL;
const int mod = 1000000007;
const int MAXN = 100010;
int n, m, u, v, x, y, t, a, b, ans, node, cnt;
bool ok[MAXN];
bool mark[MAXN];
vector<int> G[MAXN];
vector<int> out;
void dfs(int node, int par) {
  mark[node] = true;
  cnt -= ok[node];
  ok[node] ^= 1;
  for (int v : G[node]) {
    if (mark[v]) continue;
    out.push_back(v);
    dfs(v, node);
    out.push_back(node);
    ok[node] ^= 1;
  }
  if (ok[node] && par) {
    out.push_back(par);
    out.push_back(node);
    ok[par] ^= 1;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m;
  while (m--) {
    cin >> u >> v;
    G[u].push_back(v);
    G[v].push_back(u);
  }
  for (int i = 1; i <= n; i++) {
    cin >> ok[i];
    if (ok[i]) cnt++;
    if (!node && ok[i]) node = i;
  }
  if (!node) return cout << 0 << '\n', 0;
  ;
  dfs(node, 0);
  if (cnt) return cout << -1 << '\n', 0;
  ;
  if (!ok[node])
    cout << out.size() + 1 << endl << node << ' ';
  else
    cout << out.size() << endl;
  for (int i : out) cout << i << ' ';
  cout << endl;
  return 0;
}
