include [HTML_REMOVED]

include [HTML_REMOVED]

include [HTML_REMOVED]

using namespace std;
const int N=100010;//

struct Node
{
int e,aim;
}p[N];
int a[N];
long long ans;
int main()
{
int n;
scanf(“%d”, &n);
for(int i=1;i<=n;i++)scanf(“%d”,&a[i]);

for(int i=1;i<=n/2;i++){
    int aim=a[n-i+1];
    p[i]={a[i],aim};
    p[n-i+1]={a[n-i+1],a[n-i+1]};
    //cout<<p[i].e<<" "<<p[i].aim<<"    ";
}
if(n/2)p[n/2+1]={a[n/2+1],a[n/2+1]};
for(int i=1;i<=n/2;i++)
{
    //cout<<p[i].e<<" "<<p[i].aim<<"    ";
    int j=i+1;
    int cnt1=p[i].aim-p[i].e;
    int cnt2=p[j].aim-p[j].e;
    //cout<<cnt1<<" "<<cnt2<<endl;
    if(cnt1*cnt2>0){

        if(abs(cnt1)>=abs(cnt2)){
            ans+=(long long)abs(cnt1);
            p[j].e=p[j].aim;
        }
        else{
            ans+=(long long)cnt2;
            p[j].e=p[j].aim;
        }
    }
    else{
        ans+=abs(cnt1);
    }
}
printf("%lld",ans);
return 0;

}