#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long long lint;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

lint N;
vector<lint> a;

lint solve(vector<lint> v) {
    lint N = v.size();

    vector<lint> sum = {v[0]}, pfx, sfx;

    for (int i=1; i<N; i++) sum.push_back(sum[i-1] + v[i]);

    pfx.resize(N);
    sfx.resize(N);

    pfx[0] = sum[0];
    for (int i=1; i<N; i++) pfx[i] = max(pfx[i-1], sum[i]);

    sfx[N-1] = sum[N-1];
    for (int i=N-2; i>=0; i--) sfx[i] = max(sfx[i+1], sum[i]);

    lint ans = 0;
    for (int k=0; k+1<N; k++) {
        lint now = -2 * sum[k];

        if (k > 0) now += pfx[k-1];
        now += sfx[k+1];

        ans = max(ans, now);
    }

    return ans;
}

int main()
{
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    
    cin >> N;

    a.resize(N);
    for (int i=0; i<N; i++) cin >> a[i];

    lint ans = solve(a);

    reverse(a.begin(), a.end());

    ans = max(ans, solve(a));

    cout << ans << '\n';
}