#include <bits/stdc++.h> #define int long long #ifndef ONLINE_JUDGE #define DEBUG #endif const int N = 1e7+10; using namespace std;

int a[N], pfx[N], pmin[N], pmax[N];

signed main() { ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

memset(pmin, 0x3f, sizeof pmin);
memset(pmax, 0xcf, sizeof pmax);

int n;cin>>n;

for(int i=1;i<=n;i++) {
	cin>>a[i];
	pfx[i] = pfx[i-1] + a[i];
	pmin[i] = min(pmin[i-1], pfx[i]);
	pmax[i] = max(pmax[i-1], pfx[i]);
}

pmin[0] = pmax[0] = 0;

int situation1 = -1e14, situation2 = -1e14;

for(int r=2;r<=n;r++) {
	situation1 = max(situation1, pfx[r] - pmin[r-1]);
}

for(int r=2;r<=n;r++) {
	int tmp = pfx[r] - pmax[r-1];
	situation2 = max(situation2, pfx[n] - tmp);
}

cout<<max(situation1, situation2);

return 0;

}