#include <cstdio>
#include <iostream>
using namespace std;
const int N = 1e6;
const int maxn = 1e6 + 5;
const long long mod = 998244353;
long long fpm(long long x, long long y) {
    long long res = 1ll;
    if (y < 0) y += mod - 1;
    for (; y; y >>= 1, x = x * x % mod)
        if (y & 1) res = res * x % mod;
    return res;
}
long long fac[maxn], inv[maxn];
long long C(int n, int m) {
    if (n < m) return 0ll;
    return fac[n] * inv[m] % mod * inv[n - m] % mod;
}
int T, n, m;
int a[maxn];
int main() {
    fac[0] = 1;
    for (int i = 1; i <= N; i++) fac[i] = fac[i - 1] * (long long)i % mod;
    inv[N] = fpm(fac[N], -1);
    for (int i = N; i >= 1; i--) inv[i - 1] = inv[i] * (long long)i % mod;
    scanf("%d", &T);
    while (T--) {
        scanf("%d%d", &n, &m);
        int mn = N;
        for (int i = 1; i <= m; mn = min(mn, a[i++])) scanf("%d", a + i);
        int cnt = n - m - (mn ? (mn - 1) : 0);
        long long ans = (mn ? ((long long)(m + 1) * fac[mn] % mod) : 1ll) * fac[n] % mod * inv[m + mn] % mod;
        printf("%lld\n", ans);
    }
    return 0;
}