#include <bits/extc++.h>
using namespace std;

#define int long long

#define pii pair<int, int>

signed main() {
#ifdef CB
	ifstream fin("be2.txt");
	cin.rdbuf(fin.rdbuf());
	ofstream fout("ki.txt");
#endif
	int A, B;
	cin >> A >> B;
	vector<int> a(A), b(B);
	for (int i = 0; i < A; i++) {
		cin >> a[i];
	}
	for (int i = 0; i < B; i++) {
		cin >> b[i];
	}
	vector<int> l(A);
	for (int i = 0; i < A; i++) {
		int c = 0;
		for (int j = 0; j < B; j++) {
			if (b[j] > a[i]) {
				l[i] = max(l[i], c);
				c = 0;
			}
			else {
				c++;
			}
		}
		l[i] = max(l[i], c);
	}
	int ans = 0;
	for (int i = 0; i < A; i++) {
		int mi = i;
		for (int j = i; j < A; j++) {
			if (a[j] < a[mi]) {
				mi = j;
			}
			ans = max(ans, (j - i + 1) * l[mi]);
		}
	}
	cout << ans << endl;
	return 0;
}