#include <bits/stdc++.h>

using i64 = long long;

constexpr int N = 5005;
constexpr int p = 998244353;

int fac[N];

void init() {
    fac[0] = 1;
    for (int i = 1; i < N; i ++ ) {
        fac[i] = 1LL * fac[i - 1] * i % p;
    }
}

void inc(int &a, int b) {
    a += b;
    if (a >= p) {
        a -= p;
    }
}

void sub(int &a, int b) {
    a -= b;
    if (a < 0) {
        a += p;
    }
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    init();

    int n, k;
    std::cin >> n >> k;

    std::vector<int> a(n);
    for (int i = 0; i < n; i ++ ) {
        std::cin >> a[i];
    }

    std::vector<int> cnt;
    std::vector<bool> vis(n);
    for (int i = 0; i < n; i ++ ) {
        if (!vis[i]) {
            int x = 0;
            for (int j = i; j < n; j ++ ) {
                if (a[j] == a[i] + x * k) {
                    x ++ ;
                    vis[j] = true;
                }
            }
            cnt.push_back(x);
        }
    }

    std::vector<int> f(n);
    f[0] = 1;
    for (auto x : cnt) {
        std::vector dp(x, std::vector<std::array<int, 2>>(x));
        dp[0][0][0] = 1;
        for (int i = 1; i < x; i ++ ) {
            for (int j = 0; j <= i; j ++ ) {
                inc(dp[i][j][0], dp[i - 1][j][0]);
                inc(dp[i][j][0], dp[i - 1][j][1]);
                if (j > 0) {
                    inc(dp[i][j][1], dp[i - 1][j - 1][1]);
                    inc(dp[i][j][1], dp[i - 1][j - 1][0] * 2 % p);
                }
            }
        }
        std::vector<int> g(n);
        for (int i = 0; i < n; i ++ ) {
            for (int j = 0; j < x && i + j < n; j ++ ) {
                inc(g[i + j], 1LL * f[i] * dp.back()[j][0] % p);
                inc(g[i + j], 1LL * f[i] * dp.back()[j][1] % p);
            }
        }
        f = std::move(g);
    }

    int ans = 0;
    for (int i = 0; i < n; i ++ ) {
        if (i % 2) {
            sub(ans, 1LL * f[i] * fac[n - i] % p);
        } else {
            inc(ans, 1LL * f[i] * fac[n - i] % p);
        }
    }
    std::cout << ans << "\n";

    return 0;
}