//#define NDEBUG
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <iostream>
#include <utility>
#include <vector>

namespace n91 {

using i8 = std::int_fast8_t;
using i32 = std::int_fast32_t;
using i64 = std::int_fast64_t;
using u8 = std::uint_fast8_t;
using u32 = std::uint_fast32_t;
using u64 = std::uint_fast64_t;
using isize = std::ptrdiff_t;
using usize = std::size_t;

struct rep {
  struct itr {
    usize i;
    constexpr itr(const usize i) noexcept : i(i) {}
    void operator++() noexcept { ++i; }
    constexpr usize operator*() const noexcept { return i; }
    constexpr bool operator!=(const itr x) const noexcept { return i != x.i; }
  };
  const itr f, l;
  constexpr rep(const usize f, const usize l) noexcept
      : f(std::min(f, l)), l(l) {}
  constexpr auto begin() const noexcept { return f; }
  constexpr auto end() const noexcept { return l; }
};
struct revrep {
  struct itr {
    usize i;
    constexpr itr(const usize i) noexcept : i(i) {}
    void operator++() noexcept { --i; }
    constexpr usize operator*() const noexcept { return i; }
    constexpr bool operator!=(const itr x) const noexcept { return i != x.i; }
  };
  const itr f, l;
  constexpr revrep(const usize f, const usize l) noexcept
      : f(l - 1), l(std::min(f, l) - 1) {}
  constexpr auto begin() const noexcept { return f; }
  constexpr auto end() const noexcept { return l; }
};
template <class T> auto md_vec(const usize n, const T &value) {
  return std::vector<T>(n, value);
}
template <class... Args> auto md_vec(const usize n, Args... args) {
  return std::vector<decltype(md_vec(args...))>(n, md_vec(args...));
}
template <class T> constexpr T difference(const T &a, const T &b) noexcept {
  return a < b ? b - a : a - b;
}
template <class T> void chmin(T &a, const T &b) noexcept {
  if (b < a)
    a = b;
}
template <class T> void chmax(T &a, const T &b) noexcept {
  if (a < b)
    a = b;
}
template <class F> class fix_point : private F {
public:
  explicit constexpr fix_point(F &&f) : F(std::forward<F>(f)) {}

  template <class... Args>
  constexpr decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, std::forward<Args>(args)...);
  }
};
template <class F> constexpr decltype(auto) make_fix(F &&f) {
  return fix_point<F>(std::forward<F>(f));
}
template <class T> T scan() {
  T ret;
  std::cin >> ret;
  return ret;
}

} // namespace n91
#include <map>
#include <set>
namespace n91 {

void main_() {
  /*
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  //*/
  const usize n = scan<usize>();
  const usize m = scan<usize>();
  std::vector<u32> a(n);
  std::vector<int> b(n + 1, 0);
  {
    std::vector<std::pair<usize, int>> ps(n);
    for (auto &e : ps)
      std::cin >> e.first >> e.second;
    std::sort(ps.begin(), ps.end());
    int prev = 0;
    for (const usize i : rep(0, n)) {
      a[i] = ps[i].first;
      b[i] = prev ^ ps[i].second;
      prev = ps[i].second;
    }
    b[n] = prev;
  }
  const auto idx = [&](const u32 x) -> usize {
    return std::lower_bound(a.cbegin(), a.cend(), x) - a.cbegin();
  };
  std::map<std::pair<usize, usize>, usize> mp;
  std::vector<std::vector<usize>> g(n + 1);
  for (const usize i : rep(0, m)) {
    const usize l = idx(scan<u32>());
    const usize r = idx(scan<u32>() + 1);
    mp[{l, r}] = i;
    g[l].push_back(r);
    g[r].push_back(l);
  }
  std::set<usize> st;
  std::vector<bool> used(n + 1, false);
  const auto dfs = make_fix([&](const auto &dfs, const usize v) -> void {
    used[v] = true;
    for (const usize e : g[v]) {
      if (used[e])
        continue;
      dfs(e);
      if (b[e]) {
        st.insert(mp[std::minmax(v, e)]);
        b[e] ^= 1;
        b[v] ^= 1;
      }
    }
  });
  for (const usize i : rep(0, n + 1))
    dfs(i);
  if (std::all_of(b.cbegin(), b.cend(), [](const auto x) { return x == 0; })) {
    std::cout << st.size() << std::endl;
    for (const auto e : st)
      std::cout << e + 1 << " ";
  } else {
    std::cout << "-1";
  }
  std::cout << std::endl;
}

} // namespace n91

int main() {
  n91::main_();
  return 0;
}


Measured memory_bytes: 30692