#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    int c=1,ans=0;
    int a[n+1],b[n/2];
    for(int i=1;i<=n;i++){
    	cin>>a[i];
	}
	for(int i=1;i<=n/2;i++){
		b[i]=abs(a[i]-a[n-i+1]);
	}
	sort(b+1,b+1+n/2);
	while(1){
		if(!b[n/2-1]){
		    if(c==n/2-1)break;
		    else{swap(b[n/2-1],b[c]);c++;}
		}
		if(b[n/2]){
			b[n/2]-=b[n/2-1];
			ans+=b[n/2-1];
			b[n/2-1]=0;
		}
		else{
			swap(b[n/2],b[n/2-1]);
		}
	}
	cout<<ans+b[n/2]<<endl;
	return 0;
}