#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
const int inf = 0x3f3f3f, maxn = 5e5 + 500;
long long gcd(long long x, long long y) {
  if (y == 0)
    return x;
  else
    return gcd(y, x % y);
}
long long ksm(long long a, long long b) {
  long long r = 1;
  while (b) {
    if (b & 1) r = (r * a) % mod;
    a = a * a % mod;
    b >>= 1;
  }
  return r;
}
int n, m, f[maxn][25] = {0};
int query(int l, int r) {
  int sum = 0;
  for (int i = 23; i >= 0; i--) {
    if (f[l][i] < r && f[l][i] != 0) {
      l = f[l][i];
      sum += (1 << i);
    }
  }
  if (f[l][0] < r) return -1;
  return sum + 1;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  cin >> n >> m;
  int max1 = 0;
  for (int i = 1; i <= n; i++) {
    int l, r;
    cin >> l >> r;
    f[l][0] = max(f[l][0], r);
    max1 = max(r, max1);
  }
  for (int l = 0; l <= max1; l++)
    if (l != 0) f[l][0] = max(f[l][0], max(l, f[l - 1][0]));
  for (int j = 1; j <= 23; j++)
    for (int l = 0; l <= max1; l++) f[l][j] = f[f[l][j - 1]][j - 1];
  for (int i = 1; i <= m; i++) {
    int l, r;
    cin >> l >> r;
    int ans = query(l, r);
    cout << ans << endl;
  }
}
