#include<iostream>
#include<algorithm>
#include<random>
#include<vector>
#include<chrono>
#include<cmath>
#include<queue>
#include<set>
#include<map>
#define pii pair<int,int>
#define int long long
using namespace std;
signed main(){
    int n;
    cin>>n;
    int all[n+1];
    int dp[n+1];
    int rdp[n+1];
    for(int i=1;i<=n;i++){
        cin>>all[i];
    }
    for(int i=1;i<=n;i++){
        if(i==1){
            dp[i]=all[i];
        }else {
            dp[i]=max(dp[i-1]+all[i],all[i]);
        }
    }
    for(int i=n;i>=1;i--){
        if(i==n){
            rdp[i]=all[i];
        }else rdp[i]=min(all[i],rdp[i+1]+all[i]);
    }
    int ans=-1e10;
    for(int i=1;i<n;i++){
        //cout<<dp[i]<<" "<<rdp[i+1]<<endl;
        ans=max(ans,dp[i]-rdp[i+1]);
    }
    cout<<ans<<endl;

    return 0;
}