#include <bits/stdc++.h>
using namespace std;
int n, m;
int ans = INT_MIN;
void dp_cal(vector<int> a, vector<int> b){
	vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));
	for(int i = 1; i <= n; i++){
		for(int j = 1; j <= m; j++){
			dp[i][j] = max(dp[i][j], dp[i - 1][i - 1] + a[i] * b[j]);
			ans = max(dp[i][j], ans); 
		}
	}
}
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	cin >> n >> m;
	vector<int> a(n + 1);
	vector<int> b(m + 1);
	for(int i = 1; i <= n; i++){
		cin >> a[i];
	}
	for(int i = 1; i <= m; i++){
		cin >> b[i];
	}
	dp_cal(a, b);
 	reverse(a.begin() + 1, a.end());
	dp_cal(a, b);
	cout << ans;
 
}

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NSA1Ci0zIC0zIDMgMyAtMwoyIDIgMiAyIDI=

5 5
-3 -3 3 3 -3
2 2 2 2 2