#include <bits/stdc++.h>

using namespace std;

const int N = 1005, P = 998244353;

void add(int &x, int y) {
    ((x += y) >= P) && (x -= P);
}

int a[N], pw[N], f[2][105][105][105];

signed main() {
    int n; scanf("%d", &n);
    for (int i = pw[0] = 1; i <= n; ++i) scanf("%d", &a[i]), pw[i] = 2 * pw[i - 1] % P;
    a[n + 1] = a[n] + 1;
    int res = 0;
    f[1][0][0][0] = 1;
    for (int i = 1; i <= n; ++i) {
        for (int j = 0; j <= 75; ++j) {
            for (int k = 0; k <= 75; ++k) {
                for (int l = 0; l <= 75; ++l) {
                    int v = f[i & 1][j][k][l], D = a[i + 1] - a[i];
                    if (!v) continue;
                    f[i & 1][j][k][l] = 0;
                    add(f[(i & 1) ^ 1][max(j - D, 0)][max(k - D, 0)][max(l - D, 0)], v);
                    if (!j) {
                        res = (res + 1ll * v * pw[n - i]) % P;
                        add(f[(i & 1) ^ 1][max(max(k, 20) - D, 0)][max(max(l, 20) - D, 0)][max(75 - D, 0)], v);
                    } else {
                        add(f[(i & 1) ^ 1][max(j - D, 0)][max(max(k, 20) - D, 0)][max(max(l, 20) - D, 0)], v);
                    }
                }
            }
        }
    }
    printf("%d\n", res * 2 % P);
    return 0;
}