#include <bits/stdc++.h>
using namespace std;
long long dx[] = {1, 0, -1, 0};
long long dy[] = {0, 1, 0, -1};
long long gcd(long long x, long long y) {
  if (y == 0)
    return x;
  else
    return gcd(y, x % y);
}
long long expo(long long n, long long m, long long p) {
  long long r = 1;
  n = n % p;
  while (m > 0) {
    if (m % 2) r = (r * n) % p;
    n = (n * n) % p;
    m = m / 2;
  }
  return r % p;
}
bool isPrime(long long n) {
  if (n <= 1) return false;
  if (n <= 3) return true;
  if (n % 2 == 0 || n % 3 == 0) return false;
  for (long long i = 5; i * i <= n; i = i + 6)
    if (n % i == 0 || n % (i + 2) == 0) return false;
  return true;
}
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long n, m;
  cin >> n >> m;
  vector<long long> a(n), b(m);
  for (long long i = 0; i < n; i++) {
    cin >> a[i];
  }
  for (long long i = 0; i < m; i++) {
    cin >> b[i];
  }
  vector<long long> an;
  for (long long i = 0; i < n; i++) {
    vector<long long> bn;
    for (long long j = 0; j < m; j++) {
      for (long long k = 0; k < n; k++) {
        if (k != i) {
          bn.push_back(b[j] * a[k]);
        }
      }
    }
    sort(bn.begin(), bn.end());
    an.push_back(bn[bn.size() - 1]);
  }
  sort(an.begin(), an.end());
  cout << an[0] << '\n';
}
