#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = long double;
using str = string;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;
using vi = vector<int>;
using vb = vector<bool>;
using vc = vector<char>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;
template <class T>
using V = vector<T>;
const ll MOD = 1e9 + 7;
const int MX = 2e+5;
const ll INF = 1e18;
const db PI = acos((db)-1);
const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
constexpr int pct(int x) { return __builtin_popcount(x); }
constexpr int bits(int x) { return x == 0 ? 0 : 31 - __builtin_clz(x); }
constexpr int p2(int x) { return 1 << x; }
constexpr int msk2(int x) { return p2(x) - 1; }
void setIO() {
  cin.tie(0)->sync_with_stdio(0);
  cin.exceptions(cin.failbit);
}
int main() {
  setIO();
  int n, m;
  cin >> n >> m;
  vi a(n), b(n), c(m), d(m);
  for (int i = (0); i < (n); ++i) cin >> a[i] >> b[i];
  for (int i = (0); i < (m); ++i) cin >> c[i] >> d[i];
  const int MAX = 1e6 + 1;
  vi res(MAX);
  for (int i = (0); i < (n); ++i) {
    for (int j = (0); j < (m); ++j) {
      if (a[i] <= c[j])
        res[c[j] - a[i]] = max(res[c[j] - a[i]], d[j] - b[i] + 1);
    }
  }
  int ans = MAX;
  int mx = 0;
  for (int i = (MAX)-1; i >= (0); --i) {
    mx = max(mx, res[i]);
    ans = min(ans, i + mx);
  }
  cout << ans << endl;
  return 0;
}
