import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.InputMismatchException;
import java.util.List;

public class Main {

	private static final String NO = "NO";
	private static final String YES = "YES";
	InputStream is;
	PrintWriter out;
	String INPUT = "";

	private static final long MOD = 1000000007;
	private static final int INF = Integer.MAX_VALUE;

	void solve() {
		int T = 1;
		for (int i = 0; i < T; i++)
			solve(i);
	}

	int n;
	private List<int[]>[] g;
	private int[] a;
	private List<Integer> ans = new ArrayList<Integer>();

	void solve(int T) {
		int n = ni();
		int m = ni();
		int p[][] = na(n, 2);
		Comparator<int[]> c = new Comparator<int[]>() {
			public int compare(int[] o1, int[] o2) {
				if (o1[0] == o2[0])
					return o1[1] - o2[1];
				return o1[0] - o2[0];
			}
		};
		Arrays.sort(p, c);

		a = new int[n + 1];
		a[0] = p[0][1];
		for (int i = 1; i < n; i++)
			a[i] = p[i][1] ^ p[i - 1][1];
		a[n] = p[n - 1][1];
		g = new List[n + 1];
		vis = new boolean[n + 1];
		for (int i = 0; i <= n; i++)
			g[i] = new ArrayList<int[]>();
//		tr(p);
//		tr(a);
		for (int i = 0; i < m; i++) {
			int s = ni();
			int e = ni();

			int l = Arrays.binarySearch(p, new int[] { s, 0 }, c);
			if (l < 0)
				l = -l - 1;
			int r = Arrays.binarySearch(p, new int[] { e + 1, 0 }, c);
			if (r < 0)
				r = -r - 1;
//			tr(s, e, l, r);
			g[l].add(new int[] { r, i + 1 });
			g[r].add(new int[] { l, i + 1 });
		}

		for (int i = 0; i <= n; i++) {
			if (!vis[i]) {
				if (dfs(i)) {
					out.println("-1");
					return;
				}

			}
		}

		out.println(ans.size());
		Collections.sort(ans);
		for (int i : ans)
			out.print(i + " ");
	}

	private boolean dfs(int x) {
		vis[x] = true;
		boolean rt = a[x] == 1;
		for (int[] v : g[x]) {
			int y = v[0];
			if (vis[y])
				continue;
			boolean t = dfs(y);
			if (t)
				ans.add(v[1]);
			rt ^= t;
		}
		return rt;
	}

	// a^b
	long power(long a, long b) {
		long x = 1, y = a;
		while (b > 0) {
			if (b % 2 != 0) {
				x = (x * y) % MOD;
			}
			y = (y * y) % MOD;
			b /= 2;
		}
		return x % MOD;
	}

	private long gcd(long a, long b) {
		while (a != 0) {
			long tmp = b % a;
			b = a;
			a = tmp;
		}
		return b;
	}

	void run() throws Exception {
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);

		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if (!INPUT.isEmpty())
			tr(System.currentTimeMillis() - s + "ms");
	}

	public static void main(String[] args) throws Exception {
		new Main().run();
	}

	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	private boolean vis[];

	private int readByte() {
		if (lenbuf == -1)
			throw new InputMismatchException();
		if (ptrbuf >= lenbuf) {
			ptrbuf = 0;
			try {
				lenbuf = is.read(inbuf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (lenbuf <= 0)
				return -1;
		}
		return inbuf[ptrbuf++];
	}

	private boolean isSpaceChar(int c) {
		return !(c >= 33 && c <= 126);
	}

	private int skip() {
		int b;
		while ((b = readByte()) != -1 && isSpaceChar(b))
			;
		return b;
	}

	private double nd() {
		return Double.parseDouble(ns());
	}

	private char nc() {
		return (char) skip();
	}

	private String ns() {
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != '
									// ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	private char[] ns(int n) {
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while (p < n) {
			if (!(isSpaceChar(b)))
				buf[p++] = (char) b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}

	private char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for (int i = 0; i < n; i++)
			map[i] = ns(m);
		return map;
	}

	private int[] na(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = ni();
		return a;
	}

	private List<Integer> na2(int n) {
		List<Integer> a = new ArrayList<Integer>();
		for (int i = 0; i < n; i++)
			a.add(ni());
		return a;
	}

	private int[][] na(int n, int m) {
		int[][] a = new int[n][];
		for (int i = 0; i < n; i++)
			a[i] = na(m);
		return a;
	}

	private int ni() {
		int num = 0, b;
		boolean minus = false;
		while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
			;
		if (b == '-') {
			minus = true;
			b = readByte();
		}

		while (true) {
			if (b >= '0' && b <= '9') {
				num = num * 10 + (b - '0');
			} else {
				return minus ? -num : num;
			}
			b = readByte();
		}
	}

	private long[] nl(int n) {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nl();
		return a;
	}

	private long[][] nl(int n, int m) {
		long[][] a = new long[n][];
		for (int i = 0; i < n; i++)
			a[i] = nl(m);
		return a;
	}

	private long nl() {
		long num = 0;
		int b;
		boolean minus = false;
		while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
			;
		if (b == '-') {
			minus = true;
			b = readByte();
		}

		while (true) {
			if (b >= '0' && b <= '9') {
				num = num * 10 + (b - '0');
			} else {
				return minus ? -num : num;
			}
			b = readByte();
		}
	}

	private static void tr(Object... o) {
		System.out.println(Arrays.deepToString(o));
	}
}

Measured memory_bytes: 97720