#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
template <typename T> inline void read(T &FF) {
    int RR = 1; FF = 0; char CH = getchar();
    for(; !isdigit(CH); CH = getchar()) if(CH == '-') RR = -RR;
    for(; isdigit(CH); CH = getchar()) FF = FF * 10 + CH - 48;
    FF *= RR;
}
inline void file(string str) {
    freopen((str + ".in").c_str(), "r", stdin);
    freopen((str + ".out").c_str(), "w", stdout);
}
const int N = 3e2 + 10;
const LL mod = 1e9 + 7;
LL c[N][N]; int n, k, flag[N], cnt[N];
void init() {
	for(int i = 0; i <= n; i++) {
		c[i][0] = 1;
		for(int j = 1; j <= i; j++)
			c[i][j] = (c[i - 1][j] + c[i - 1][j - 1]) % mod;
	}
}
vector<LL> calc(const vector<LL> &p) {
	vector<LL> q(p.size()); q[0] = 1;
	for(int i = 1; i < q.size(); i++) {
		for(int j = 1; j <= i; j++)
			q[i] += c[i - 1][j - 1] * p[j] % mod * q[i - j] % mod;
		q[i] %= mod;
	}
	return q;
}
LL Qpow(LL x, LL k) {
	if(k <= 1) return k ? x : 1;
	LL h = Qpow(x, k / 2); h = h * h % mod;
	return k & 1 ? h * x % mod : h;
}
int main() {
    //file("");
	read(n), read(k); init();
	for(int i = 1; i <= k; i++) flag[i] = 1;
	vector<LL> G; G.emplace_back(0);
	for(int i = 1; i <= n; i++) {
		vector<LL> F = G;
		for(int j = 0; j < i; j++) F[j] = F[j] * i % mod;
		auto K = calc(F);
		LL s = flag[i] * Qpow(i, i);
		for(int j = 1; j < i; j++)
			s = (s + mod - c[i - 1][j - 1] * K[i - j] % mod * F[j] % mod) % mod;
		G.emplace_back(s * Qpow(i, mod - 2) % mod);
	}
	for(int i = 1; i <= n; i++) G[i] = G[i] * n % mod;
	G = calc(G);
	for(int i = 1; i <= n; i++) {
		int x; read(x); cnt[x]++;
	}
	LL ans = Qpow(n, mod - 2); ans = ans * ans % mod;
	for(int i = 1; i <= n; i++) 
		ans = ans * G[cnt[i]] % mod;
	cout << ans << '\n';
    return 0;
}