#include <bits/stdc++.h>
 
const int maxn = 1e6 + 5;
typedef long long ll;
 
int n;
ll a[maxn];
 
int main() {
	freopen("Unnamed_Problem.in","r",stdin);
	freopen("Unnamed_Problem.out","w",stdout);
	scanf("%d",&n);
	for(int i = 1;i <= n;++ i)scanf("%lld",&a[i]);
	
	std::sort(a + 1 , a + 1 + n);
	
	ll ans = std::min(a[1] - (a[n] * a[n]) / (4 * a[2]) , a[2] - (a[n] * a[n]) / (4 * a[1]));
	printf("%lld",ans);
	return 0;
}