#include <bits/stdc++.h>
using namespace std;
#define int long long int
#define double long double
inline int power(int a, int b) {
int x = 1;
while (b) {
if (b & 1) x *= a;
a *= a;
b >>= 1;
}
return x;
}
const int M = 1000000007;
const int N = 3e5+9;
const int INF = 2e9+1;
const int LINF = 2000000000000000001;
//_ ***************************** START Below *******************************
vector<int> a;
int consistency(int n) {
vector<int> prefixMaxiDp(n);
vector<int> sufixMaxiDp(n);
int maxi = -INF;
int last = 0;
for(int i=0; i<n; i++){
int curr = max(last + a[i], a[i]);
last = curr;
maxi = max(maxi, curr);
prefixMaxiDp[i] = maxi;
}
last = 0;
maxi = -INF;
for(int i=n-1; i>=0; i--){
int curr = max(last + a[i], a[i]);
last = curr;
maxi = max(maxi, curr);
sufixMaxiDp[i] = maxi;
}
int ans = -INF;
for(int i=0; i<n-1; i++){
ans = max(ans, prefixMaxiDp[i] + sufixMaxiDp[i+1]);
}
return ans;
}
int practice(int n) {
return 0;
}
void solve() {
int n;
cin >> n;
a.resize(n);
for(int i=0; i<n; i++) cin >> a[i];
cout << consistency(n) << endl ;
// cout << consistency(n) << " -> " << practice(n) << endl;
}
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int t = 1;
while (t--) {
solve();
}
return 0;
}
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