#include <iostream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <cassert>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <string>
#include <algorithm>
#include <utility>
#include <complex>
#define rep(x, s, t) for(llint (x) = (s); (x) <= (t); (x)++)
#define chmin(x, y) (x) = min((x), (y))
#define chmax(x, y) (x) = max((x), (y))
#define all(x) (x).begin(),(x).end()
#define inf 1e18
#define mod 998244353

using namespace std;

typedef long long llint;
typedef long long ll;
typedef pair<llint, llint> P;

ll n;
ll a[2505], b[2505];
ll dp[2505], sum[2505];

int main(void)
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n;
	rep(i, 1, n) cin >> a[i];
	
	ll dmax = 0;
	rep(i, 1, n-1) chmax(dmax, a[i+1]-a[i]);
	
	rep(i, dmax, 2500){
		rep(j, 1, n) dp[j] = 0;
		rep(j, 1, n-1){
			ll p = lower_bound(a+1, a+n+1, a[j+1]-i) - a;
			dp[j] = sum[j-1] - sum[p-1] + 1, dp[j] %= mod;
			sum[j] = sum[j-1] + dp[j], sum[j] %= mod;
		}
		b[i] = dp[n-1]*2%mod;
	}
	
	ll ans = 0;
	rep(i, 1, 2500) ans += (b[i]-b[i-1]+mod)%mod * i % mod, ans %= mod;
	cout << ans << endl;
	
	return 0;
}