#include <bits/stdc++.h>
using namespace std;
template <class T>
bool maximize(T &x, const T &y) {
  if (x < y)
    x = y;
  else
    return false;
  return true;
}
const int N = 5e5 + 10;
int n, q, md;
int dx[N];
int d[N][21];
int query(int x, int y) {
  if (d[x][20] < y) return -1;
  int ret = 0;
  for (int i = 20; i >= 0; i--)
    if (d[x][i] < y) {
      x = d[x][i];
      ret += 1 << i;
    }
  return ret + 1;
}
int main() {
  if (fopen("exam.inp", "r"))
    freopen("exam.inp", "r", stdin), freopen("exam.out", "w", stdout);
  scanf("%d%d", &n, &q);
  for (int i = 1; i <= n; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    maximize(dx[x], y);
    maximize(md, y);
  }
  for (int i = 1; i <= md; i++) maximize(dx[i], dx[i - 1]);
  for (int i = 0; i <= md; i++) d[i][0] = dx[i];
  for (int j = 1; j <= 20; j++)
    for (int i = 0; i <= md; i++) d[i][j] = d[d[i][j - 1]][j - 1];
  while (q--) {
    int x, y;
    scanf("%d%d", &x, &y);
    printf("%d\n", query(x, y));
  }
}
