using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
static class Program{
	const int mod=(int)1e9+7;
	static List<Tuple<int,int>>[] li;
	static List<int> ans;
	static bool[] ba;
	static int[] g;
	static void Main(){
		Sc sc=new Sc();
		var s=sc.Ia;
		var a=sc.Arr(s[0],()=>sc.Ia);
		var b=new int[s[1]][];
		var c=new int[s[1]][];
		var d=new int[s[1]][];
		for(int i = 0;i<s[1];i++) {
			var e=sc.Ia;
			b[i]=new int[]{e[0],i};
			c[i]=new int[]{e[1],i};
			d[i]=new int[]{s[0]+1,s[0]+1};
		}
		var h=new int[s[0]+2];
		g=new int[s[0]+2];
		Array.Sort(a,(u,v)=>u[0]-v[0]);
		Array.Sort(b,(u,v)=>u[0]-v[0]);
		Array.Sort(c,(u,v)=>u[0]-v[0]);
		int n=s[0]+1;
		li=new List<Tuple<int,int>>[n+1];
		for(int i = 0,j=0,k=0;i<s[0];i++) {
			h[i+1]=a[i][1];
			g[i+1]=h[i]==h[i+1]?0:1;
			while(j<s[1]&&b[j][0]<=a[i][0]){
				d[b[j][1]][0]=i+1;
				j++;
			}
			while(k<s[1]&&c[k][0]<a[i][0]){
				d[c[k][1]][1]=i+1;
				k++;
			}
			li[i+1]=new List<Tuple<int,int>>();
		}
		li[n]=new List<Tuple<int,int>>();
		if(h[s[0]]==1){g[s[0]+1]=1;}
		ba=new bool[n+1];
		ans=new List<int>();
		for(int i = 0;i<d.Length;i++) {
			if(d[i][0]!=d[i][1]){
				li[d[i][0]].Add(Tuple.Create(d[i][1],i+1));
				li[d[i][1]].Add(Tuple.Create(d[i][0],i+1));
			}
		}
		for(int i=1;i<=n;i++){
			if(!ba[i]){
				Fu(i);
				if(g[i]==1){
					Console.WriteLine(-1);
					return;
				}
			}
		}
		ans.Sort();
		Console.WriteLine(ans.Count);
		Console.WriteLine("{0}",String.Join(" ",ans));
	}
	static void Fu(int a){
		ba[a]=true;
		for(int i=0;i<li[a].Count;i++){
			if(!ba[li[a][i].Item1]){
				Fu(li[a][i].Item1);
				if(g[li[a][i].Item1]==1){
					g[a]^=1;
					ans.Add(li[a][i].Item2);
				}
			}
		}
	}
}
public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),int.Parse);}
	public int[] Ia3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),long.Parse);}
	public long[] La3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),long.Parse);}
	public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}}
	public double[] Da3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),double.Parse);}
	public double[] Da3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),double.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
}

Measured memory_bytes: 81428