#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <tuple>
#include <cstdint>
#include <cstdio>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <deque>
#include <unordered_map>
#include <unordered_set>
#include <bitset>
#include <cctype>
#include <functional>
#include <ctime>
#include <fstream>
#include <cmath>
#include <limits>
#include <chrono>
#include <numeric>
#include <type_traits>
#include <iomanip>
#include <float.h>
#include <math.h>
#include <cassert>
#include <atcoder/all>
using namespace atcoder;
#pragma warning (disable: 4996)
using namespace std;

using ll = long long;
unsigned euclidean_gcd(unsigned a, unsigned b) {
    if (a < b) return euclidean_gcd(b, a);
    unsigned r;
    while ((r = a % b)) {
        a = b;
        b = r;
    }
    return b;
}

ll ll_gcd(ll a, ll b) {
    if (a < b) return ll_gcd(b, a);
    ll r;
    while ((r = a % b)) {
        a = b;
        b = r;
    }
    return b;
}

struct UnionFind {
    vector <ll> par;
    vector <ll> siz;
    UnionFind(ll sz_) : par(sz_), siz(sz_, 1LL) {
        for (ll i = 0; i < sz_; ++i) par[i] = i;
    }
    void init(ll sz_) {
        par.resize(sz_);
        siz.assign(sz_, 1LL);
        for (ll i = 0; i < sz_; ++i) par[i] = i;
    }
    ll root(ll x) {
        while (par[x] != x) {
            x = par[x] = par[par[x]];
        }
        return x;
    }
    bool merge(ll x, ll y) {
        x = root(x);
        y = root(y);
        if (x == y) return false;
        if (siz[x] < siz[y]) swap(x, y);
        siz[x] += siz[y];
        par[y] = x;
        return true;
    }

    bool issame(ll x, ll y) {
        return root(x) == root(y);
    }

    ll size(ll x) {
        return siz[root(x)];
    }
};

long long modpow(long long a, long long n, long long mod) {
    if (n < 0)return 0;
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

long long modinv(long long a, long long mod) {
    return modpow(a, mod - 2, mod);
}

ll merge_cnt(vector<ll>& a) {
    int n = a.size();
    if (n <= 1) { return 0; }

    ll cnt = 0;
    vector<ll> b(a.begin(), a.begin() + n / 2);
    vector<ll> c(a.begin() + n / 2, a.end());

    cnt += merge_cnt(b);
    cnt += merge_cnt(c);

    int ai = 0, bi = 0, ci = 0;
    while (ai < n) {
        if (bi < b.size() && (ci == c.size() || b[bi] <= c[ci])) {
            a[ai++] = b[bi++];
        }
        else {
            cnt += n / 2 - bi;
            a[ai++] = c[ci++];
        }
    }
    return cnt;
}


long long extGCD(long long a, long long b, long long& x, long long& y) {
    if (b == 0) {
        x = 1;
        y = 0;
        return a;
    }
    long long d = extGCD(b, a % b, y, x);
    y -= a / b * x;
    return d;
}

ll op(ll a,ll b) {
    return (a + b) % 998244353;
}

ll e() {
    return 0;
}

int main() {
    ll n, k;
    cin >> n >> k;
    vector<ll> x(k);
    vector<ll> z(n-k);
    vector<pair<ll, ll>> d(n-k);
    for (int i = 0; i < k; i++) {
        cin >> x[i];
    }
    for (int i = 0; i < n-k; i++) {
        cin >> z[i];
        d[i].first = z[i];
        d[i].second = i;
    }
    sort(x.begin(), x.end());
    ll ans = 0;
    for (int i = 0; i < n - k; i++) {
        ll r = modpow(k-1, i+1, 998244353) * modinv(modpow(k, i+1, 998244353),998244353) % 998244353*modinv(2,998244353);
        ll ok = -1;
        ll ng = k;
        while (ng - ok > 1) {
            ll mid = (ok + ng) / 2;
            if (x[mid] < z[i])ok = mid;
            else ng = mid;
        }
        ok++;
        ans += (ok * r + (k - ok) * (998244354 - r)) % 998244353;
        ans %= 998244353;
    }
    sort(d.begin(), d.end());
    segtree<ll, op, e> t(n-k);
    segtree<ll, op, e> f(n - k);
    ll h = 1;
    for (int i = 0; i < n-k; i++) {
        t.set(i,h);
        h *= (k-1) * modinv(k,998244353) % 998244353;
        h %= 998244353;
    }
    for (int i = 0; i < n - k; i++) {
        ll g = t.prod(d[i].second+1, n-k);
        ans += g * modinv(t.get(d[i].second), 998244353) % 998244353*modinv(2,998244353) % 998244353;
        t.set(d[i].second, 0);
        ans %= 998244353;
    }
    reverse(d.begin(), d.end());
    for (int i = 0; i < n - k; i++) {
        t.set(i, h);
        h *= (k-1) * modinv(k, 998244353) % 998244353;
        h %= 998244353;
    }
    for (int i = 0; i < n - k; i++) {
        ll g = t.prod(d[i].second+1, n-k);
        ans += n-k-d[i].second-1+998244353-(g * modinv(t.get(d[i].second), 998244353) % 998244353 * modinv(2, 998244353) % 998244353);
        ans += f.prod(d[i].second + 1, n - k);
        t.set(d[i].second, 0);
        f.set(d[i].second, 998244352);
        
        ans %= 998244353;
    }
    ans += k * (k-1)/2 % 998244353 * modinv(2,998244353) % 998244353;
    ans %= 998244353;
    cout << ans << endl;
}