#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;
}