#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int n,m;
    cin>>n>>m;
    vector<pair<int,int>> utak(n+1);
    for(int i=1;i<=n;i++)
        {
        cin>>utak[i].first>>utak[i].second;
        }
    int tovabbm=1;
    int tovabbmtmp=1;
    int indextmp;
    vector<int> megoldas(10001);
    int cnt=0;
    for(int i=1;i<=n;)
        {
        if(utak[i].first<=tovabbm)
            {
            if(utak[i].second>tovabbmtmp)
                {
                tovabbmtmp=utak[i].second;
                indextmp=i;
                }
            i++;
            }
        else
            {
            if(tovabbm==tovabbmtmp)
                {
                cout<<-1<<" "<<tovabbm;
                return 0;
                }
            else
                {
                tovabbm=tovabbmtmp;
                megoldas[cnt]=indextmp;
                cnt++;
                }
            }
        }
    cout<<cnt<<endl;
    for(int i=0;i<cnt;i++)
        {
        cout<<megoldas[i]<<" ";
        }
    return 0;
}