#include<bits/stdc++.h>
using namespace std;
#define nl "\n"
#define fi first
#define se second
#define pb push_back
#define ll long long
#define RV return void
#define sz(x) int(x.size())
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()


struct Node{
    int sum , pref , suff , mx;

    Node(){
        sum  = mx = pref = suff = 0;
    }
    void change(int x){
        sum = mx = pref = suff = x;
    }
};

struct SegTree{
    int tree_size;
    vector<Node> tree;

    SegTree(int n){
        tree_size = 1;
        while (tree_size < n) tree_size *= 2;
        tree.assign(2 * tree_size, Node());
    }

    Node merge(Node &left, Node &right){
        Node ans = Node();
        ans.sum = left.sum + right.sum;
        ans.pref = max(left.pref, left.sum + right.pref);
        ans.suff = max(right.suff, left.suff + right.sum);
        ans.mx = max({left.mx, right.mx, left.suff + right.pref});
        return ans;
    }

    void build(vector<int> & v, int node, int lx, int rx){
        if(rx - lx == 1){
            if(lx < sz(v) )
                tree[node].change(v[lx]);
            return;
        }
        int md = lx + (rx - lx) / 2;

        build(v, 2 * node + 1, lx, md);
        build(v, 2 * node + 2, md, rx);

        tree[node] = merge(tree[2 * node + 1], tree[2 * node + 2]);
    }

    void build(vector<int> & v){
        build(v, 0, 0, tree_size);
    }

    Node get(int l, int r, int node, int lx, int rx){
        if(lx >= l and rx <= r)
            return tree[node];
        if(lx >= r or rx <= l)
            return Node();

        int md = lx + (rx - lx) / 2;

        Node left = get(l, r, 2 * node + 1, lx, md);
        Node right = get(l, r, 2 * node + 2, md, rx);

        return merge(left, right);
    }

    Node get(int l, int r){
        return get(l, r, 0, 0, tree_size);
    }
};


void solve(){

    int n; cin >> n;
    vector < int > v(n), nxt(n), prv(n);
    for(auto& x : v) cin >> x;

    stack < int > st;
    for(int i = n - 1; i >= 0; i--){
        while(!st.empty() and v[st.top()] <= v[i]) st.pop();
        nxt[i] = (st.empty() ? n-1 : st.top() - 1);
        st.push(i);
    }

    stack < int > st2;
    for(int i = 0; i < n; i++){
        while(!st2.empty() and v[st2.top()] <= v[i]) st2.pop();
        prv[i] = (st2.empty() ? 0 : st2.top() + 1);
        st2.push(i);
    }

    // for(int i =0 ; i < n ; i++){
    //     cout << v[i] <<  " " << prv[i] << " " << nxt[i] << nl;
    // }

    SegTree seg(n);
    seg.build(v);

    int ans=0;
    for(int i =0 ; i < n ; i++){
        //  suppose we must delete v[i]
        int l = prv[i] , r = nxt[i] ;
        auto temp = seg.get(l,r+1);

        if(temp.l <= l and temp.r >= r ){
            //  valid
            ans = max(ans, temp.mx - v[i]);
        }
    }

    cout << ans ;





}


int main(){
    ios_base::sync_with_stdio(false),cin.tie(nullptr),cout.tie(nullptr);
    int t=1;
        // cin >> t ;
    for(int i=1 ; i <= t ; i++){
        solve();
    }
    return 0;
}