#include <bits/stdc++.h>
using namespace std;
#define _rep(i_,a_,b_) for(int i_ = (a_); i_ <= (b_); ++i_)
#define mid ((L+R) >> 1)
#define multiCase() int testCnt = in(); _rep(curCase,1,testCnt)
#ifdef ONLINE_JUDGE
#define debug(...) 0
#else
#define debug(...) fprintf(stderr, __VA_ARGS__), fflush(stderr)
#endif
using ll = long long;
using pii = pair<int,int>;

int in(void) { int x; scanf("%d", &x); return x; } ll inl(void) { ll x; scanf("%lld", &x); return x; }
void out(int x) { printf("%d ", x); } void outln(int x) { printf("%d\n", x); }
void out(ll x) { printf("%lld ", x); } void outln(ll x) { printf("%lld\n", x); }
template<typename T> void chkmax(T &a, const T &b) { a = max(a, b); } 
template<typename T> void chkmin(T &a, const T &b) { a = min(a, b); } 
const int kN = 205000, p = 998244353, G = 3;
int a[kN], fac[kN], iv[kN], ifac[kN], ans[kN];
int C(int n, int m) {
	if(n < m) return 0;
	return 1ll * fac[n] * ifac[m] % p * ifac[n - m] % p;
}
int fpm(int a, int b) {
	int r = 1;
	for(;b;b >>= 1, a = 1ll * a * a % p) if(b & 1) r = 1ll * r * a % p;
	return r;
}
int f[1 << 21], g[1 << 21], h[1 << 21];
int r[1 << 21], l, L;
void NTT(int *A, int n) {
	_rep(i,0,n - 1) if(i < r[i]) swap(A[i], A[r[i]]);
	for(int i = 1; i < n; i <<= 1) {
		int W = fpm(G, (p - 1) / i / 2);
		for(int j = 0; j < n; j += i << 1) {
			int w = 1;
			_rep(k,0,i - 1) {
				int x = (A[j + k] + 1ll * w * A[j + k + i]) % p, 
					y = (A[j + k] - 1ll * w * A[j + k + i] % p + p) % p;
				A[j + k] = x, A[j + k + i] = y;
				w = 1ll * w * W % p;
			}
		}
	}
}
int main() {
	fac[0] = ifac[0] = 1;
	_rep(i,1,200000) fac[i] = 1ll * fac[i - 1] * i % p;
	iv[1] = 1; _rep(i,2,200000) iv[i] = 1ll * iv[p % i] * (p - p / i) % p;
	_rep(i,1,200000) ifac[i] = 1ll * ifac[i - 1] * iv[i] % p;
	multiCase() { 
		int n = in(), m = in();
		_rep(i,1,n * m) a[i] = in();
		sort(a + 1, a + n * m + 1); int N = n * m; a[N + 1] = 0;
		_rep(i,0,N) f[i] = g[i] = 0;
		_rep(i,0,n) _rep(j,0,m) if(i + j) {
			int tot = i * m + j * n - i * j;
			int g = 1ll * C(n, i) * C(m, j) % p * fac[tot] % p * fac[n * m - tot] % p;
			if((i + j) % 2 == 0) g = (p - g);
			f[tot] = (f[tot] + g) % p;
		}
		_rep(i,0,N) f[i] = 1ll * f[i] * ifac[i] % p, g[i] = ifac[i];
		l = 0; while((1 << l) <= N * 2) ++l; L = 1 << l;
		_rep(i,N + 1,L - 1) f[i] = g[i] = 0;
		_rep(i,1,L - 1) r[i] = (r[i >> 1] >> 1) | ((i & 1) << (l - 1));
		NTT(f, L), NTT(g, L);
		_rep(i,0,L - 1) f[i] = 1ll * f[i] * g[i] % p;
		NTT(f, L); reverse(f + 1, f + L); int iv = fpm(L, p - 2);
		_rep(i,0,L - 1) f[i] = 1ll * f[i] * iv % p * fac[i] % p;
		int res = 0, cnt = 0, lst = 0;
		_rep(k,1,N) if(a[k] != a[k + 1]) {
			res = (res + 1ll * a[k] * (f[k] - lst)) % p;
			lst = f[k];
		}
		outln(res);
	}
	return 0;
}