#include <bits/stdc++.h>
using namespace std;
 
int main(){
    int n; cin>>n;
    // assuming array's length is at least 7
    vector<int> a(n); for(int &x:a) cin>>x;
    vector<pair<int,int>> P[2]; 
    P[0].resize(n,{0,INT_MAX}); // products on the left 
    P[1].resize(n,{0,INT_MAX}); // products on the right
    // we'll start filling from P[2] because 
    // first two elements of the array cannot be multiplied.
    int mx = a[0],mn = a[0]; // max_element(0,0) and min_element(0,0)
    for(int i=2;i<n;i++) {
        P[0][i] = P[0][i-1];
        P[0][i].first = max(P[0][i].first,a[i]*mx);
        P[0][i].second = min(P[0][i].second,a[i]*mn);
        mx = max(mx,a[i-1]); mn = min(mn,a[i-1]);
    }
    // we'll start from P[n-3] because
    // last two elements of the arrays cannot be multiplied.
    mx = a[n-1],mn = a[n-1]; // max_element(n-1,n-1) and min_element(n-1,n-1)
    for(int i=n-3;i>=0;i--){
        P[1][i] = P[1][i+1];
        P[1][i].first = max(P[1][i].first,a[i]*mx);
        P[1][i].second = min(P[1][i].second,a[i]*mn);
        mx = max(mx,a[i+1]); mn = min(mn,a[i+1]);
    }
    int ans = 0;
    for(int i=2;i<n-3;i++){
        ans = max(ans,max(P[0][i].first-P[0][i+1].second,P[1][i+1].first-P[1][i].second));
    }
    cout<<ans;
    return 0;
}

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