#include <bits/stdc++.h>
using namespace std;

signed main() {
    int n, m;
    cin >> n >> m;
    vector<pair<int,int>> v(m+1);
    for (int i = 1; i <= n; i++) {
        int a, b;
        cin >> a >> b;
        v[a]=max(v[a],{b,i});
    }
    for (int i = 1; i <= m; i++) {
        v[i]=max(v[i],v[i-1]);
    }
    int x = 1;
    vector<int> ansv;
    while (x<m) {
        if (v[x].first<=x) {
            cout << -1;
            return 0;
        }
        ansv.push_back(v[x].second);
        x=v[x].first;
    }
    cout<<ansv.size()-1<<endl;
    for (int x : ansv)cout << x << ' ';
}