#include<iostream>
#include<algorithm>
#include<iomanip>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<string>
#include<cmath>
#include<set>
#include<queue>
#include<stack>
#include<map>
#define PI acos(-1.0)
#define in freopen("in.txt", "r", stdin)
#define out freopen("out.txt", "w", stdout)
#define kuaidian ios::sync_with_stdio(0);
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
const int maxn = 100 + 7, maxd = 1e5 + 7;
const int mod = 1e9 + 7;
const ll INF = 0x7f7f7f7f7f7f7f7f;
int n, m;
ll a[maxn], b[maxn], ans[maxd];
int main() {
cin >> n >> m;
for(int i = 0; i < n; ++i) cin >> a[i];
for(int i = 0; i < m; ++i) cin >> b[i];
int id = 0;
for(int i = 0; i < n; ++i) {
ll t = -INF;
for(int j = 0; j < m; ++j) {
t = max(t, a[i]*b[j]);
}
ans[i] = t;
}
sort(ans, ans+n);
cout << ans[n-2];
return 0;
}
