#include <bits/stdc++.h>

using namespace std;

int n, m;
vector<int> a;
vector<int> b;
vector<int> ut (0);
bool eljut = true;

void bejar(int c)
{
    int max = -1;
    for (int i = 0; i < n; i++)
    {
        if (a[i] <= c && b[i] > c && (max == -1 || b[max] < b[i]))
        {
            max = i;
        }
    }
    ut.push_back(max);
    if (max == -1)
    {
        eljut = false;
    }
    else if (b[max] != m)
    {
        bejar(b[max]);
    }
}

int main()
{
    cin >> n >> m;
    a.resize (n);
    b.resize (n);
    for (int i = 0; i < n; i++)
    {
        cin >> a[i] >> b[i];
    }
    bejar(1);
    if (eljut)
    {
        cout << ut.size() -1 << endl;
        for (int i = 0; i < ut.size(); i++)
        {
            cout << ut[i] +1 << " ";
        }
    }
    else
    {
        cout << -1;
    }
    return 0;
}