#include<bits/stdc++.h>

#define ll long long
#define mk make_pair
#define fi first
#define se second

using namespace std;

inline int read(){
	int x=0,f=1;char c=getchar();
	for(;(c<'0'||c>'9');c=getchar()){if(c=='-')f=-1;}
	for(;(c>='0'&&c<='9');c=getchar())x=x*10+(c&15);
	return x*f;
}

const int mod=998244353;
int ksm(int x,ll y,int p=mod){
	int ans=1;y%=(p-1);
	for(int i=y;i;i>>=1,x=1ll*x*x%p)if(i&1)ans=1ll*ans*x%p;
	return ans%p;
}
int inv(int x,int p=mod){return ksm(x,p-2,p)%p;}
mt19937 rnd(time(0));
int randint(int l,int r){return rnd()%(r-l+1)+l;}
void add(int &x,int v){x+=v;if(x>=mod)x-=mod;}
void Mod(int &x){if(x>=mod)x-=mod;}
int cmod(int x){if(x>=mod)x-=mod;return x;}

template<typename T>void cmax(T &x,T v){x=max(x,v);}
template<typename T>void cmin(T &x,T v){x=min(x,v);}

const int N=3005;
int n,pos[N],tl[N],tr[N];
ll f[2][N][N];

const ll INF=1e15;

void clr(){
	for(int i=0;i<=n;i++)pos[i]=tl[i]=tr[i]=0;
	for(int c=0;c<=1;c++)for(int i=0;i<=n;i++)for(int j=0;j<=n;j++)f[c][i][j]=INF;
}

void solve(){
	if(n==1)return puts("0"),void();
	pos[0]=-1e6,pos[n+1]=2e6;
	
	tl[1]=1,tr[1]=2,tl[n]=n-1,tr[n]=n;
	for(int i=2;i<=n-1;i++){
		int len=max(pos[i]-pos[i-1],pos[i+1]-pos[i]);
		tl[i]=lower_bound(pos+1,pos+n+1,pos[i]-len)-pos;
		tr[i]=upper_bound(pos+1,pos+n+1,pos[i]+len)-pos-1;
	}
	
	auto sq=[&](int x){return 1ll*x*x;};
	
	int cur=0;
	f[cur][1][2]=sq(pos[2]-pos[1]);
	for(int i=2;i<=n;i++){
		memset(f[cur^1],63,sizeof(f[cur^1]));
		for(int j=1;j<=i-1;j++)for(int k=i;k<=n;k++)if(f[cur][j][k]<=INF){
//			cout<<"f "<<i-1<<" "<<j<<" "<<k<<" = "<<f[cur][j][k]<<endl;
			int jj=(j==i-1?i:j);
			cmin(f[cur^1][jj][k],f[cur][j][k]+sq(pos[i]-pos[i-1]));
			if(i+1<=n){
				cmin(f[cur^1][j][max(k,i+1)],f[cur][j][k]+sq(pos[i+1]-pos[i]));
				jj=(tl[i]<=j?i:j);
				cmin(f[cur^1][jj][max(k,tr[i])],f[cur][j][k]+sq(max(pos[i]-pos[i-1],pos[i+1]-pos[i])));
			}
		}
		cur^=1;
	}
	cout<<f[cur][n][n]<<endl;
	
	clr();
}

signed main(void){

#ifndef ONLINE_JUDGE
	freopen("in.in","r",stdin);
#endif

	memset(f,63,sizeof(f));
	while(cin>>n){
		for(int i=1;i<=n;i++)cin>>pos[i];
		solve();
	}

	return 0;
}