#include <bits/stdc++.h>
using namespace std;
int n, m, tt, fa[500005][20];
pair<int, int> a[500005], b[500005];
bool cmp(pair<int, int> i, pair<int, int> j) {
  return i.first == j.first ? i.second > j.second : i.first < j.first;
}
int main() {
  ios::sync_with_stdio(0);
  cin >> n >> m;
  for (int i = 1; i <= n; i++) cin >> a[i].first >> a[i].second;
  sort(a + 1, a + n + 1, cmp);
  int tmp = 0;
  for (int i = 1; i <= n; i++) {
    if (a[i].second <= tmp) continue;
    tmp = a[i].second;
    b[++tt] = a[i];
  }
  n = tt;
  for (int i = 1; i <= n; i++) {
    pair<int, int> res = make_pair(b[i].second, 1 << 30);
    int it = upper_bound(b + 1, b + n + 1, res) - b;
    it--;
    fa[i][0] = it;
  }
  for (int i = 1; i <= 19; i++)
    for (int j = 1; j <= n; j++) fa[j][i] = fa[fa[j][i - 1]][i - 1];
  for (int i = 1, l, r; i <= m; i++) {
    cin >> l >> r;
    pair<int, int> res = make_pair(l + 1, 0);
    int it = upper_bound(b + 1, b + n + 1, res) - b;
    it--;
    if (b[it].second >= r) {
      cout << 1 << endl;
      continue;
    }
    if (b[fa[it][19]].second < r) {
      cout << -1 << '\n';
      continue;
    }
    int now = it, st = 0;
    for (int i = 19; i >= 0; i--)
      if (b[fa[now][i]].second < r) now = fa[now][i], st += (1 << i);
    st += 2;
    cout << st << '\n';
  }
}
