///////////////////////////////////////////////////////////////////////////////

#include <bits/stdc++.h>
#include <unistd.h>
#include <time.h>
#include <sys/time.h>

using namespace std;

///////////////////////////////////////////////////////////////////////////////

#define DEBUG 0

#define pb push_back
#define V vector
#define M unordered_map
#define S static

#define rep(i,n) for(ll i=0LL; i<n; ++i)
#define srep(i,s,n) for(ll i=s; i<n; ++i)
#define rrep(i,n) for(ll i=n-1LL; i>=0LL; --i)
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define CIN(x) do { \
        assert(!cin.eof()); \
        cin >> x; \
        assert(!cin.fail()); \
} while(0);
#if DEBUG
#define debug_print(...) _debug_print(__VA_ARGS__)
#define debug_printf(...) printf(__VA_ARGS__)
#define debug_print_time _debug_print_time
#else // DEBUG
#define debug_print(...)
#define debug_printf(...)
#define debug_print_time
#endif // DEBUG

typedef long long ll;
typedef unsigned long long ull;
typedef tuple<ll, ll> t2;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;
typedef tuple<ll, ll, ll, ll, ll> t5;
template <typename T>
using priority_queue_incr = priority_queue<T, V<T>, greater<T> >;

///////////////////////////////////////////////////////////////////////////////

template <typename TT, typename T>
T get_m(M<TT, T> &m, TT k, T default_value)
{
    if (m.find(k) == m.end()) return m[k] = default_value;
    return m[k];
}

template <typename TT, typename T>
void incr_m(M<TT, T> &m, TT k)
{
    if (m.find(k) == m.end()) m[k] = 0;
    m[k]++;
}

template <typename TT, typename T>
void incr_m(map<TT, T> &m, TT k)
{
    if (m.find(k) == m.end()) m[k] = 0;
    m[k]++;
}

void llin(ll &a)
{
    CIN(a);
}

void llinl1(V<ll> &v, ll count)
{
    for (ll i = 0LL; i < count; ++i) {
        ll a;
        CIN(a);
        v.push_back(a);
    }
}

void llinl2(V<t2> &v, ll count)
{
    for (ll i = 0LL; i < count; ++i) {
        ll a, b;
        CIN(a >> b);
        v.push_back(t2(a, b));
    }
}

void llinl3(V<t3> &v, ll count)
{
    for (ll i = 0LL; i < count; ++i) {
        ll a, b, c;
        CIN(a >> b >> c);
        v.push_back(t3(a, b, c));
    }
}

void llinl4(V<t4> &v, ll count)
{
    for (ll i = 0LL; i < count; ++i) {
        ll a, b, c, d;
        CIN(a >> b >> c >> d);
        v.push_back(t4(a, b, c, d));
    }
}

void llina(V<ll> &v, ll count)
{
    llinl1(v, count);
}

template <typename T>
void sort(V<T> &v)
{
    sort(v.begin(), v.end());
}

template <typename T>
void sort_reverse(V<T> &v)
{
    sort(v.begin(), v.end(), greater<T>());
}

template <typename T>
void _debug_print(T x)
{
    cout << x << endl;
}

void _debug_print(const t2 &x)
{
    ll x1 = get<0>(x);
    ll x2 = get<1>(x);
    cout << "-- " << x1 << " -- " << x2 << endl;
}

void _debug_print(const t3 &x)
{
    ll x1 = get<0>(x);
    ll x2 = get<1>(x);
    ll x3 = get<2>(x);
    cout << "-- " << x1 << " -- " << x2 << " -- " << x3 << endl;
}

void _debug_print(const t4 &x)
{
    ll x1 = get<0>(x);
    ll x2 = get<1>(x);
    ll x3 = get<2>(x);
    ll x4 = get<3>(x);
    cout << "-- " << x1 << " -- " << x2
         << " -- " << x3 << " -- " << x4 << endl;
}

template <typename T>
void _debug_print(T xarray[], ll n)
{
    rep (i, n) _debug_print(xarray[i]);
}

template <typename T>
void _debug_print(const V<T> &xlist)
{
    for (auto x : xlist) {
        cout << "-- ";
        _debug_print(x);
    }
}

template <typename T>
void _debug_print(const set<T> &xset)
{
    for (auto x : xset) {
        cout << "-- ";
        _debug_print(x);
    }
}

template <typename TT, typename T>
void _debug_print(const M<TT, T> &xlist)
{
    for (auto x : xlist) {
        TT k = x.first;
        T v = x.second;
        cout << "====" << endl;
        cout << "K=";
        _debug_print(k);
        cout << "V=";
        _debug_print(v);
    }
}

template <typename TT, typename T>
void _debug_print(const map<TT, T> &xlist)
{
    for (auto x : xlist) {
        TT k = x.first;
        T v = x.second;
        cout << "====" << endl;
        cout << "K=";
        _debug_print(k);
        cout << "V=";
        _debug_print(v);
    }
}

void _debug_print_time(const char *prefix)
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
#if DEBUG
    struct tm *tm = localtime(&tv.tv_sec);
#endif
    debug_printf("-- %s %02d:%02d:%02d.%06ld\n",
                 prefix, tm->tm_hour, tm->tm_min, tm->tm_sec, tv.tv_usec);
}


struct UnionFind
{
    ull *parent, *count, *rank;

    UnionFind(ull n) {
        parent = new ull[n+1];
        count = new ull[n+1];
        rank = new ull[n+1];
        for (ull i = 0ULL; i < n+1; ++i) {
            parent[i] = i;
            count[i] = 1;
            rank[i] = 0;
        }
    }

    ~UnionFind() {
        delete rank;
        delete count;
        delete parent;
    }

    ull root(ull i) {
        if (parent[i] == i) return i;
        parent[i] = root(parent[i]);
        return parent[i];
    }

    void unite(ull i, ull j) {
        ull rooti = root(i);
        ull rootj = root(j);

        if (rooti == rootj) return;

        if (rank[rootj] < rank[rooti]) {
            parent[i] = parent[j] = parent[rootj] = rooti;
            count[rooti] += count[rootj];
        }
        else {
            parent[i] = parent[j] = parent[rooti] = rootj;
            count[rootj] += count[rooti];
            if (rank[rootj] == rank[rooti]) rank[rootj]++;
        }
    }

    bool same(ull i, ull j) {
        return root(i) == root(j);
    }
};

struct UnionFindM
{
    M<ull, ull> parent, count, rank;

    ull root(ull i) {
        ull parent_i = get_m(parent, i, i);
        if (parent_i == i) return i;
        return parent[i] = root(parent_i);
    }

    void unite(ull i, ull j) {
        ull rooti = root(i);
        ull rootj = root(j);

        if (rooti == rootj) return;

        if (get_m(rank, rootj, 0ULL) < get_m(rank, rooti, 0ULL)) {
            parent[i] = parent[j] = parent[rootj] = rooti;
            count[rooti] = get_m(count, rooti, 1ULL) + get_m(count, rootj, 1ULL);
        }
        else {
            parent[i] = parent[j] = parent[rooti] = rootj;
            count[rootj] = get_m(count, rootj, 1ULL) + get_m(count, rooti, 1ULL);
            if (get_m(rank, rootj, 0ULL) == get_m(rank, rooti, 0ULL)) rank[rootj]++;
        }
    }

    bool same(ull i, ull j) {
        return root(i) == root(j);
    }
};




void make_edgelist(const V<t2> &srclist, V<ll> edgelist[])
{
    for (auto src : srclist) {
        ll a = get<0>(src);
        ll b = get<1>(src);
        edgelist[a].pb(b);
        edgelist[b].pb(a);
    }
}



void make_parental_relation(const V<ll> edgelist[], ll root,
                            ll parents[], V<ll> children[], ll levels[])
{
    queue<ll> q;
    set<ll> checked;

    q.push(root);
    checked.insert(root);
    parents[root] = root;
    levels[root] = 0LL;

    for ( ; !(q.empty()); ) {
        ll now = q.front(); q.pop();
        for (auto next : edgelist[now]) {
            if (checked.find(next) != checked.end()) continue;
            q.push(next);
            checked.insert(next);
            parents[next] = now;
            children[now].pb(next);
            levels[next] = levels[now] + 1LL;
        }
    }
}



///////////////////////////////////////////////////////////////////////////////

void _main();
int main()
{
    cout << setprecision(12);
#if !DEBUG
    ios::sync_with_stdio(false);
    cin.tie(0);
#endif

    _main();
    return 0;
}

void _main()
{
    ll n; llin(n);
    ll m; llin(m);
    S V<t2> ablist; llinl2(ablist, n);
    S V<t2> lrlist; llinl2(lrlist, m);

    ablist.pb(t2(-1, 0));
    ablist.pb(t2(1e10, 0));
    n += 2;
    sort(ablist);

    S map<t2, ll> uvmap;
    rep (i, m) {
        ll left = get<0>(lrlist[i]);
        ll right = get<1>(lrlist[i]);
        auto iterl = lower_bound(ALL(ablist), t2(left, -1));
        auto iterr = upper_bound(ALL(ablist), t2(right, 2));
        ll u = iterl - ablist.begin();
        ll v = iterr - ablist.begin();
        if (u == v) continue;
        uvmap[t2(u, v)] = i;
    }

    debug_printf("---- uvmap\n");
    debug_print(uvmap);

    S set<ll> vvset;
    srep (v, 1, n) {
        ll b0 = get<1>(ablist[v-1]);
        ll b1 = get<1>(ablist[v]);
        if (b0 != b1) vvset.insert(v);
    }

    debug_printf("---- vvset\n");
    debug_print(vvset);

    S UnionFind uf(100020);
    S V<t2> uvlist;
    for (auto item : uvmap) {
        t2 uv = item.first;
        ll u = get<0>(uv);
        ll v = get<1>(uv);
        if (uf.same(u, v)) continue;
        uvlist.pb(t2(u, v));
        uf.unite(u, v);
    }

    S V<ll> edgelist[100020];
    make_edgelist(uvlist, edgelist);

    S set<ll> roots;
    rep (v, n+4) roots.insert(uf.root(v));

    S set<ll> vsets[100020];
    rep (v, n+4) vsets[uf.root(v)].insert(v);

    S ll parents[100020];
    S V<ll> children[100020];
    S ll levels[100020];
    S ll childcnts[100020];
    S bool modes[100020] = {};
    S set<ll> anslist;

    for (auto root : roots) {

        ll vvcnt = 0;
        for (auto v : vsets[root]) {
            if (vvset.find(v) == vvset.end()) continue;
            vvcnt++;
            modes[v] = true;
        }
        if (vvcnt & 1LL) {
            debug_printf("---- ans -1\n");
            cout << -1 << endl;
            return;
        }

        make_parental_relation(edgelist, root, parents, children, levels);

        queue<ll> q;

        for (auto v : vsets[root]) {
            childcnts[v] = children[v].size();
            if (!childcnts[v]) q.push(v);
        }

        while (q.size()) {
            ll v = q.front(); q.pop();
            ll pv = parents[v];
            if (v == pv) continue;
            if (modes[v]) {
                ll idx = uvmap.at(t2(min(v, pv), max(v, pv)));
                anslist.insert(idx);
                modes[pv] = !modes[pv];
            }
            childcnts[pv]--;
            if (!childcnts[pv]) q.push(pv);
        }
    }

    debug_printf("---- ans\n");
    cout << anslist.size() << endl;
    for (auto ans : anslist) cout << ans+1 << " ";
    cout << endl;
}

///////////////////////////////////////////////////////////////////////////////


Measured memory_bytes: 53748