#include<cstdio>

#include<algorithm>

#include<iostream>

#include<cstring>

#include<cmath>

#include<cctype>

#include<set>

#include<queue>

#include<vector>

#include<map>

#include<bitset>

using namespace std;

typedef long long LL;

inline int read() {

    int x=,f=;char ch=getchar();for(;!isdigit(ch);ch=getchar())if(ch=='-')f=-;

    for(;isdigit(ch);ch=getchar())x=x*+ch-'';return x*f;

}

const int N = ;

LL a[N], dp[N];

int main() {

    int n = read();

    for (int i = ; i <= n; ++i) a[i] = read();

    sort(a + , a + n + );

    LL mx = , mn = 1e18;

    dp[] = a[];

    for (int i = ; i <= n; ++i) {

        dp[i] = max(dp[i - ], a[i] - dp[i - ]);

    }

    cout << dp[n];

    return ;

}