include <bits/stdc++.h>

using namespace std; int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int n; cin >> n; vector<long long> a(n+1), minSuffix(n+2); for (int i = 1; i <= n; i++) cin >> a[i]; minSuffix[n] = a[n]; for (int i = n-1; i >= 1; i–) { minSuffix[i] = min(a[i], minSuffix[i+1]); } long long maxval = a[1]; long long maxsum2 = LLONG_MIN; long long ans = LLONG_MIN; for (int j = 2; j <= n-1; j++) { long long sum2 = maxval + a[j]; if (sum2 > maxsum2) maxsum2 = sum2; long long candidate = maxsum2 - minSuffix[j+1]; if (candidate > ans) ans = candidate; if (a[j] > maxval) maxval = a[j]; } cout << ans; return 0; }