#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
using namespace std;
const int Mx=1000010;
int n,c[Mx];
long long maxn,dp[Mx];
int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++) scanf("%d",&c[i]);
    sort(c+1,c+1+n); 
    for(int i=1;i<=n;i++) maxn=max(maxn,c[i]-dp[i-1]),dp[i]=maxn;
    cout<<dp[n]<<endl;
    return 0;
}