#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#include <iostream>
typedef long long ll;
using namespace std;

constexpr ll mod007 = 1000000007;
//constexpr ll mod998 = 998244353;

constexpr int mod998 = 998244353;

int N, A[100000];
ll res;

int main() {
	scanf("%d", &N);
	for (int i = 0; i < N; i++) {
		scanf("%d", &A[i]);
		if (A[i] >= mod998)A[i] -= mod998;
	}
	for (int i = 0; i < N; i++) {
		for (int j = i + 1; j < N; j++) {
			res += A[i] + A[j];
			if (A[i] + A[j] >= mod998)res -= mod998;
		}
	}
	printf("%lld\n", res);
}