#include <bits/stdc++.h>
typedef long long ll;
const int inf=1e9,K=4;
using namespace std;
namespace io{
	const int SIZE = (1 << 24) + 1;
	char ibuf[SIZE], *iS, *iT;
	char obuf[SIZE], *oS = obuf, *oT = oS + SIZE - 1, c, qu[55];
	int f, qr;
	
	#define gc() (iS == iT ? (iT = (iS = ibuf) + fread (ibuf, 1, SIZE, stdin), (iS == iT ? EOF : *iS ++)) : *iS ++)
	
	inline void flush () {
		fwrite (obuf, 1, oS - obuf, stdout);
		oS = obuf;
	}
	
	inline void putc (char x) {
		*oS ++ = x;
		if (oS == oT) flush ();
	}
	
	template <class I>
	inline void read (I &x) {
		for (f = 1, c = gc(); c < '0' || c > '9'; c = gc()) if (c == '-') f = -1;
		for (x = 0; c <= '9' && c >= '0'; c = gc()) x = x * 10 + (c & 15); 
		x = f == -1 ? -x : x;
	}
	
	template <class I>
	inline void print (I x) {
		if (!x) putc ('0'); if (x < 0) putc ('-'), x = -x;
		while (x) qu[++ qr] = x % 10 + '0',  x /= 10;
		while (qr) putc (qu[qr --]);
	}
	
	struct Flusher_ {~Flusher_(){flush();}}io_flusher_;
}
using io :: read;
using io :: putc;
using io :: print;
int n,a[5000010];
ll res=0;
vector<ll>f[5000010];
vector<int>Op[5000010];
int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++) scanf("%d",&a[i]);
	for(int i=n;i>=2;i--) a[i]-=a[i-1];
	a[n+1]=a[1]=inf;
	for(int i=1;i<=n;i++){
		Op[i].push_back(0);
		Op[i].push_back(min(a[i],a[i+1]));
		if(a[i+1]<a[i]) for(int j=i-1,lst=min(a[i],a[i+1]);j>=1&&(j>=i-K||a[j+K]<=a[j+K+1]);j--){
			lst=a[j+1]-lst;
			if(lst>a[j]) break;
			Op[j].push_back(lst);
		}
		if(a[i]<a[i+1])for(int j=i+1,lst=min(a[i],a[i+1]);j<=n&&(j<=i+K||a[j-K-1]>=a[j-K]);j++){
			lst=a[j]-lst;
			if(lst>a[j+1]) break;
			Op[j].push_back(lst);
		}
	}
	int cnt=0;
	for(int i=1;i<=n;i++) cnt+=Op[i].size();
//	cerr<<cnt;
	for(int i=1;i<=n;i++){
		sort(Op[i].begin(),Op[i].end());
		Op[i].erase(unique(Op[i].begin(),Op[i].end()),Op[i].end());
		f[i].resize(Op[i].size());
	}
	for(int i=0;i<Op[1].size();i++) f[1][i]=1ll*Op[1][i]*Op[1][i];
	for(int i=2;i<=n;i++){
		for(int j=0,k=Op[i-1].size()-1;j<Op[i].size();j++){
			while(k>=0&&Op[i-1][k]+Op[i][j]>a[i]) k--;
			if(k<0) f[i][j]=-1e18;
			else f[i][j]=f[i-1][k]+1ll*Op[i][j]*Op[i][j];
		}
		for(int j=1;j<Op[i].size();j++) f[i][j]=max(f[i][j],f[i][j-1]);
	}
	for(int i=1;i<=n;i++) res=max(res,f[i].back());
	printf("%lld\n",res);
}