#include <bits/stdc++.h>
using namespace std;
 
int main() {
    int n;cin>>n;
    vector<int> a(n);
    for(int i=0;i<n;i++) cin>>a[i];
    vector<int> p(n),s(n);
    int c=a[0];
    p[0]=a[0];
    for(int i=1;i<n;i++) {
        c=max(a[i],c+a[i]);
        p[i]=max(p[i-1],c);
    }
    c=a[n-1];
    s[n-1]=a[n-1];
    for(int i=n-2;i>=0;i--) {
        c=max(a[i],c+a[i]);
        s[i]=max(s[i+1],c);
    }
    int ans=INT_MIN;
    for(int i=0;i<n-1;i++) ans=max(ans,p[i]+s[i+1]);
    cout<<ans<<endl;
}

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NwoxIDIgLTEgNCA1IC0zIDI=

7
1 2 -1 4 5 -3 2