#include <bits/stdc++.h>
struct Segment {
  int l, r;
  Segment() {}
  Segment(int l, int r) : l(l), r(r) {}
  bool operator<(struct Segment s) const {
    if (r != s.r) return r < s.r;
    return l > s.l;
  }
  bool contains(struct Segment s) const { return l <= s.l && s.r <= r; }
};
std::vector<struct Segment> segs;
int jmp[20][200005];
int rs[200005];
int query(int L, int R) {
  int pos = std::lower_bound(rs, rs + segs.size(), R) - rs;
  if (pos == segs.size()) {
    return -1;
  }
  if (segs[pos].l <= L) return 1;
  int cost = 1;
  for (int k = 20 - 1; k >= 0; k--) {
    if (segs[jmp[k][pos]].l > L) {
      pos = jmp[k][pos];
      cost += (1 << k);
    }
  }
  if (cost > segs.size()) {
    return -1;
  } else {
    return cost + 1;
  }
}
int main() {
  int N, M;
  scanf("%d %d", &N, &M);
  for (int i = 0; i < N; i++) {
    int L, R;
    scanf("%d %d", &L, &R);
    segs.push_back({L, R});
  }
  std::sort(segs.begin(), segs.end());
  int size = 0;
  for (int i = 0; i < segs.size(); i++) {
    while (size && segs[i].contains(segs[size - 1])) {
      size--;
    }
    segs[size++] = segs[i];
  }
  segs.resize(size);
  int j = 0;
  for (int i = 0; i < segs.size(); i++) {
    while (segs[j].r < segs[i].l) {
      j++;
    }
    jmp[0][i] = j;
    rs[i] = segs[i].r;
  }
  for (int k = 1; k < 20; k++) {
    for (int i = 0; i < segs.size(); i++) {
      jmp[k][i] = jmp[k - 1][jmp[k - 1][i]];
    }
  }
  while (M--) {
    int L, R;
    scanf("%d %d", &L, &R);
    printf("%d\n", query(L, R));
  }
  return 0;
}
