#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void amin(T &x, const T &y) {
  if (y < x) x = y;
}
template <class T>
inline void amax(T &x, const T &y) {
  if (x < y) x = y;
}
template <class Iter>
void rprintf(const char *fmt, Iter begin, Iter end) {
  for (bool sp = 0; begin != end; ++begin) {
    if (sp)
      putchar(' ');
    else
      sp = true;
    printf(fmt, *begin);
  }
  putchar('\n');
}
const int SIZE = 500011;
const int LOG = 20;
int N, M;
int D[LOG][SIZE];
void MAIN() {
  scanf("%d%d", &N, &M);
  for (int i = 0, i_len = (SIZE); i < i_len; ++i) D[0][i] = i;
  for (int i = 0, i_len = (N); i < i_len; ++i) {
    int l, r;
    scanf("%d%d", &l, &r);
    amax(D[0][l], r);
  }
  int ma = 0;
  for (int i = 0, i_len = (SIZE); i < i_len; ++i) {
    amax(ma, D[0][i]);
    amax(D[0][i], ma);
  }
  for (int t = 0, t_len = (LOG - 1); t < t_len; ++t)
    for (int i = 0, i_len = (SIZE); i < i_len; ++i) D[t + 1][i] = D[t][D[t][i]];
  for (int i = 0, i_len = (M); i < i_len; ++i) {
    int l, r;
    scanf("%d%d", &l, &r);
    int ans = 1 << 29;
    int cur = 0;
    for (int t = LOG; t--;) {
      if (D[t][l] < r) {
        cur += 1 << t;
        l = D[t][l];
      } else {
        amin(ans, cur + (1 << t));
      }
    }
    if (ans == (1 << 29)) {
      puts("-1");
    } else {
      printf("%d\n", ans);
    }
  }
}
int main() {
  int TC = 1;
  for (int tc = 0, tc_len = (TC); tc < tc_len; ++tc) MAIN();
  return 0;
}
