3 2
1 0 1
1 2
2 3
 10 10
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1
6 7
8 3
6 4
4 2
9 2
5 10
9 8
10 7
5 1
6 2

2
1
2
 0

#include <bits/stdc++.h>
using namespace std;
void init_ios() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
}
const int N = 3 * (int)1e5 + 10;
int n, m, d[N], jest = -1, ile[N], par[N], sumnp;
bool vis[N];
vector<pair<int, int> > child[N];
bool napraw, wzialem[N];
map<pair<int, int>, int> ktora;
pair<int, int> yolo;
set<int> res;
bool dupa;
void dfs1(int v, int kra, int pr) {
  vis[v] = true;
  for (pair<int, int> dz : child[v])
    if (!vis[dz.first]) dfs1(dz.first, dz.second, v);
  if (d[v] == -1) return;
  if (d[v] != ile[v] % 2) {
    res.erase(kra);
    --ile[pr];
  }
}
void dfs2(int v, int kra, int pr) {
  vis[v] = true;
  par[v] = pr;
  for (pair<int, int> dz : child[v]) {
    if (!vis[dz.first]) {
      ktora[{v, dz.first}] = dz.second;
      dfs2(dz.first, dz.second, v);
    } else if (vis[dz.first] && dz.first != pr)
      yolo = {v, dz.second};
  }
  if (d[v] != ile[v] % 2 && kra != -1) {
    res.erase(kra);
    --ile[pr];
    wzialem[kra] = false;
  } else if (d[v] != ile[v] % 2 && kra == -1)
    napraw = true;
}
void dfs3(int v, int kra, int pr) {
  vis[v] = true;
  for (pair<int, int> dz : child[v])
    if (!vis[dz.first]) dfs3(dz.first, dz.second, v);
  if (d[v] != ile[v] % 2 && kra != -1) {
    res.erase(kra);
    --ile[pr];
  } else if (d[v] != ile[v] % 2 && kra == -1)
    dupa = true;
}
int main() {
  init_ios();
  cin >> n >> m;
  for (int i = 1; i <= n; ++i) {
    cin >> d[i];
    if (d[i] == -1) jest = i;
    wzialem[i] = true;
    if (d[i] == 1) sumnp += d[i];
  }
  for (int i = 1; i <= m; ++i) {
    int x, y;
    res.insert(i);
    cin >> x >> y;
    child[x].push_back({y, i});
    child[y].push_back({x, i});
    ile[x]++;
    ile[y]++;
  }
  if (jest != -1) {
    dfs1(jest, -1, -1);
    cout << res.size() << "\n";
    for (int nr : res) cout << nr << "\n";
    return 0;
  }
  if (sumnp & 1) {
    cout << "-1\n";
    return 0;
  }
  if (m > n - 1) {
    dfs2(1, -1, -1);
    if (napraw) {
      res.erase(yolo.second);
      int v = yolo.first;
      while (v != 1) {
        int kt = ktora[{par[v], v}];
        if (wzialem[kt])
          res.erase(kt);
        else
          res.insert(kt);
        v = par[v];
      }
    }
    cout << res.size() << "\n";
    for (int nr : res) cout << nr << "\n";
    return 0;
  } else {
    dfs3(1, -1, -1);
    if (dupa) {
      cout << "-1\n";
      return 0;
    }
    cout << res.size() << "\n";
    for (int nr : res) cout << nr << "\n";
    return 0;
  }
}
