#include <bits/stdc++.h>
using namespace std;

int n, a[3001000];
long long f[3001000], ans;

int main() {
	cin >> n;
	for (int i = 1; i <= n; ++i)
		cin >> a[i];
	sort(a + 1, a + 1 + n);
	for (int i = 1; i <= n; ++i)
		f[i] = max(f[i - 1], a[i] - f[i - 1]);
	cout << f[n];
	return 0;
}