/*
TASK: OTS
LANG: C++
*/
#include <iostream>
using namespace std;

int a[1000000],b[1000000],n;

void sort () {
	int i,j;
	for (i=0;i<n;i++) {
		for (j=0;j<n-1;j++) {
			if (a[j]>a[j+1]) {
				swap(a[j],a[j+1]);
			}
		}
	}
}

int main () {
	cin >> n;
	int i;
	for (i=0;i<n;i++) {
		cin >> a[i];
		b[i]=0;
	}
	sort();
	b[1]=1;
	b[n-1]=1;
	for (i=3;i<n-1;i++) {
		if (b[i-1] && b[i+1]) b[i]=0;
		if (b[i-1] && !b[i+1]) {
			if (a[i]-a[i-1]<a[i+1]-a[i]) b[i]=1;
		}
		if (!b[i-1] && !b[i+1]) {
			if (a[i]-a[i-1]<a[i-1]-a[i-1]+a[i+1]-a[i]) b[i]=1;
			if (a[i]-a[i-1]==a[i-1]-a[i-1]+a[i+1]-a[i]) b[i-1]=1;
		}
		if (!b[i] && b[i+1]) {
			if (a[i]-a[i-1]>a[i-1]-a[i-2]) b[i-1]=1;
		}
	}
	int k=0;
	for (i=0;i<n;i++) {
		if (b[i]) k+=(a[i]-a[i-1]);
	}
	cout << k << '\n';
	return 0;
}
