#include <bits/stdc++.h>
using namespace std;
long long int mod;
void prime(int a, vector<int>& v) {
  for (long long int i = 2; i * i <= a; i++) {
    if (a % i == 0) v.push_back(i);
    while (a % i == 0) {
      a = a / i;
    }
  }
  if (a > 1) v.push_back(a);
}
bool isprime(int a) {
  for (int i = 2; i * i <= a; i++)
    if (a % i == 0) return false;
  return true;
}
long long int expmod(long long int a, long long int b) {
  if (b == 1) return a;
  if (b == 0) return 1;
  long long int m1 = expmod(a, b / 2) % mod;
  if (b % 2) return ((m1 * m1) % mod * a % mod) % mod;
  return (m1 * m1) % mod;
}
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long int lcm(long long int a, long long int b) {
  return (a * b) / gcd(a, b);
}
struct myComp {
  constexpr bool operator()(pair<int, pair<int, int>> const& a,
                            pair<int, pair<int, int>> const& b) const noexcept {
    if (a.first < b.first) return true;
    if (a.first > b.first) return false;
    return a.second.first > b.second.first;
  }
};
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<int> a(n), b(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i] >> b[i];
  }
  vector<int> c(m), d(m);
  for (int i = 0; i < m; i++) {
    cin >> c[i] >> d[i];
  }
  const int MAX = 1000010;
  vector<int> v(MAX);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (a[i] <= c[j]) {
        v[c[j] - a[i]] = max(v[c[j] - a[i]], d[j] - b[i] + 1);
      }
    }
  }
  int ans = 2 * MAX;
  int mx = 0;
  for (int dx = MAX - 1; dx >= 0; dx--) {
    mx = max(mx, v[dx]);
    ans = min(ans, dx + mx);
  }
  cout << ans << '\n';
  return 0;
}
