#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <atcoder/modint>
using namespace std;
using i64 = long long;
using u64 = unsigned long long;
#define rep(i,n) for(int i=0; i<(int)(n); i++)
const i64 INF = 1001001001001001001;
const char* yn(bool x){ return x ? "Yes" : "No"; }
using Modint = atcoder::static_modint<998244353>;


void testcase(){
    int N; cin >> N;
    vector<int> A(N);
    rep(i,N) cin >> A[i];
    Modint f = 1, ff = 1;
    for(int i=1; i<N; i++){ ff *= (f *= i); }
    Modint q = 1;
    rep(i,N) A[i] += i;
    rep(i,N) rep(j,i) q *= A[i] - A[j];
    q /= ff;
    q *= q;
    cout << q.val() << endl;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    testcase();
    return 0;
}