//
// Created by lukah on 09/03/2025.
//
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5+5;
const int LOGN = 22;
const int INF = 1e9;
int L[N], R[N];
int bl[2*N][LOGN];
vector<int> pos[2*N];
int prestej(int l, int r)
{
int rez = 0;
for (int j = LOGN-1; j >= 0; j--)
if (bl[l][j] <= r)
{
l = bl[l][j];
rez += (1<<j);
}
return rez;
}
signed main()
{
int n, k;
cin >> n >> k;
map<int, int> mp;
for (int i = 0; i < n; i++)
{
cin >> L[i] >> R[i];
mp[L[i]] = 1;mp[R[i]] = 1;
}
int cur_pos = 0;
for (auto &[pos, val] : mp)
val = cur_pos++;
for (int i = 0; i < n; i++)
L[i] = mp[L[i]], R[i] = mp[R[i]];
for (int i = 0; i < n; i++)
pos[L[i]].push_back(i);
int cur_r = cur_pos;
for (int i = cur_pos; i >= 0; i--)
{
for (int j = 0; j < pos[i].size(); j++)
cur_r = min(cur_r, R[pos[i][j]]);
bl[i][0] = cur_r;
}
for (int j = 1; j < LOGN; j++)
for (int i = 0; i <= cur_pos; i++)
bl[i][j] = bl[bl[i][j - 1]][j - 1];
int cur_k = prestej(0, cur_pos-1);
if (cur_k < k)
{
cout << "-1\n";
return 0;
}
set<pair<int, int>> st;
st.insert({0, 0});
st.insert({cur_pos-1, cur_pos-1});
int i = 0;
while (st.size()-2 < k)
{
auto it = st.lower_bound({R[i], 0});
int r = it->first;
it--;
int l = it->second;
i++;
if (l > L[i-1]) continue;
int zac = cur_k - prestej(l, r) + prestej(l, L[i-1]) + prestej(R[i-1], r) + 1;
if (zac >= k)
{
cout << i<< "\n";
cur_k = zac;
st.insert({L[i-1], R[i-1]});
}
}
return 0;
}
