#include <bits/stdc++.h>
using namespace std;
const int inf = (int)1e9;
const long long INF = (long long)5e18;
const int MOD = 998244353;
int _abs(int x) { return x < 0 ? -x : x; }
int add(int x, int y) {
  x += y;
  return x >= MOD ? x - MOD : x;
}
int sub(int x, int y) {
  x -= y;
  return x < 0 ? x + MOD : x;
}
void Add(int &x, int y) {
  x += y;
  if (x >= MOD) x -= MOD;
}
void Sub(int &x, int y) {
  x -= y;
  if (x < 0) x += MOD;
}
void Mul(int &x, int y) { x = (long long)(x) * (y) % MOD; }
int qpow(int x, int y) {
  int ret = 1;
  while (y) {
    if (y & 1) ret = (long long)(ret) * (x) % MOD;
    x = (long long)(x) * (x) % MOD;
    y >>= 1;
  }
  return ret;
}
void checkmin(int &x, int y) {
  if (x > y) x = y;
}
void checkmax(int &x, int y) {
  if (x < y) x = y;
}
void checkmin(long long &x, long long y) {
  if (x > y) x = y;
}
void checkmax(long long &x, long long y) {
  if (x < y) x = y;
}
inline int read() {
  int x = 0, f = 1;
  char c = getchar();
  while (c > '9' || c < '0') {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9')
    x = (x << 1) + (x << 3) + (c ^ 48), c = getchar();
  return x * f;
}
const int N = 100005;
int t[N], vis[N], n, m, a[N];
vector<int> v[N];
namespace DSU {
int b[N], fa[N];
void init() {
  for (int i = 1; i <= n; i++) fa[i] = i, b[i] = a[i];
}
int getfather(int x) { return x == fa[x] ? x : fa[x] = getfather(fa[x]); }
void unite(int x, int y) {
  x = getfather(x);
  y = getfather(y);
  if (x == y) return;
  fa[x] = y;
  b[y] |= b[x];
}
}  // namespace DSU
vector<int> ans;
void dfs(int u) {
  vis[u] = 1;
  t[u]++;
  ans.push_back(u);
  for (auto &to : v[u])
    if (!vis[to]) {
      dfs(to);
      t[u]++;
      ans.push_back(u);
      if (t[to] % 2 != a[to]) {
        t[to]++;
        t[u]++;
        ans.push_back(to);
        ans.push_back(u);
      }
    }
}
int main() {
  n = read();
  m = read();
  for (int i = 1; i <= m; i++) {
    int x = read(), y = read();
    v[x].push_back(y);
    v[y].push_back(x);
  }
  for (int i = 1; i <= n; i++) a[i] = read();
  DSU::init();
  for (int i = 1; i <= n; i++) {
    for (auto &j : v[i]) DSU::unite(i, j);
  }
  int cnt = 0;
  for (int i = 1; i <= n; i++) cnt += (i == DSU::getfather(i) && DSU::b[i]);
  if (!cnt) {
    puts("0");
    return 0;
  }
  if (cnt >= 2) {
    puts("-1");
    return 0;
  }
  int rt;
  for (int i = 1; i <= n; i++)
    if (i == DSU::getfather(i) && DSU::b[i]) rt = i;
  dfs(rt);
  int st = (a[rt] == t[rt] % 2 ? 0 : 1);
  printf("%d\n", (int)(ans).size() - st);
  for (int i = st; i < (int)(ans).size(); i++) printf("%d ", ans[i]);
  return 0;
}
