10
4 2
7 4
2 6
2 5
4 8
10 3
2 9
9 1
5 10
 10
5 10
7 8
8 3
2 6
3 2
9 7
4 5
10 1
6 4
 4
4 1
4 3
4 2
 3
3 1
1 2
 9
1 2
1 3
1 4
1 5
1 6
6 7
6 8
8 9
 5
1 5
2 3
2 4
1 2
 8
6 1
4 7
4 8
8 5
7 6
4 3
4 2
 7
5 6
5 7
5 1
7 4
6 3
3 2
 3
1 3
3 2
 2
1 2
 5
5 4
4 3
3 1
5 2
 6
1 6
3 1
6 4
5 3
2 5
 11
8 9
2 7
1 11
3 2
9 1
8 5
8 6
5 4
4 10
8 3
 11
11 9
6 7
7 1
8 11
5 6
3 5
9 3
10 8
2 4
4 10
 12
12 6
6 7
8 11
4 8
10 4
12 3
2 10
6 2
12 9
4 1
9 5

-1
 9
 1
 1
 3
 3
 -1
 -1
 1
 1
 1
 5
 1
 5
 -1

#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7, siz = 1e6 + 5;
vector<long long> g[siz];
long long t, n, m, k, timer, dep[siz], a[siz];
vector<long long> ans;
bool vis[siz];
void go(long long u, long long p) {
  vis[u] = 1;
  ans.push_back(u);
  a[u] ^= 1;
  for (auto v : g[u]) {
    if (vis[v]) continue;
    go(v, u);
    ans.push_back(u);
    a[u] ^= 1;
  }
  if (a[u]) {
    if (p != 0) {
      ans.push_back(p);
      ans.push_back(u);
      a[p] ^= 1;
      a[u] ^= 1;
    }
  }
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> m;
  for (long long i = 1; i <= m; i++) {
    long long x, y;
    cin >> x >> y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  long long st = -1;
  for (long long i = 1; i <= n; i++) {
    cin >> a[i];
    if (a[i]) st = i;
  }
  if (st == -1) return cout << 0 << endl, 0;
  go(st, 0);
  if (a[st]) {
    ans.pop_back();
    a[st] ^= 1;
  }
  for (long long i = 1; i <= n; i++)
    if (a[i]) return cout << -1 << endl, 0;
  cout << (long long)ans.size() << endl;
  for (auto x : ans) cout << x << " ";
}
