#include<bits/stdc++.h>
#define f(i,a,n) for(int i=a;i<n;i++)
#define S second
#define F first
#define Sc(n) scanf("%lld",&n)
#define scc(a,b,c) scanf("%d %d %d",&a,&b,&c)
#define Scc(a,b,c) scanf("%lld %lld %lld",&a,&b,&c)
#define sp(a) scanf("%d %d",&a.first,&a.second)
#define Sp(a) scanf("%lld %lld",&a.first,&a.second)
#define pb push_back
#define mp make_pair
#define lb lower_bound
#define ub upper_bound
#define all(a) a.begin(),a.end()
#define sc(n) scanf("%d",&n)
#define It iterator
#define SET(a,b) memset(a,b,sizeof(a))
#define DRT()  int t; cin>>t; while(t--)
// inbuilt functions
// __gcd,  __builtin_ffs,     (returns least significant 1-bit, __builtin_ffsll(1)=1)
// __builtin_clz,             (returns number of leading zeroes in 
// __builtin_popcount,
using namespace std;
typedef long long LL;
typedef pair<int,int> PII;
typedef vector<int> vi;
#define tr(container, it) for(__typeof(container.begin()) it = container.begin(); it != container.end(); it++)
#define trv(s,it) for(auto it:s)
#define TRACE
#ifdef TRACE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__) 
template <typename Arg1> void __f(const char* name, Arg1&& arg1)
{	    cerr << name << " : " << arg1 << std::endl; }
template <typename Arg1, typename... Args> void __f(const char* names, Arg1&& arg1, Args&&... args)
{	    const char* comma = strchr(names + 1, ',');cerr.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...); }
#else
#define trace(...)
#endif
LL arr[1000006];
LL sum[1000006];
LL sqs[1000006];
int main()
{	int n,m,k,an;
	cin>>n;
	f(i,1,n+1)
	{	Sc(arr[i]);
		sum[i]+=arr[i];
		sqs[i]+=arr[i]*arr[i];
		sum[i]+=sum[i-1];
		sqs[i]+=sqs[i-1];
	}
	LL mxx=LLONG_MIN;
	f(i,1,n+1)
		f(j,i,n+1)
			mxx=max(mxx,(sum[j]-sum[i-1])*(sum[j]-sum[i-1])-sqs[j]+sqs[i-1]);
	cout<<mxx/2<<endl;
}