#include <bits/stdc++.h>
using namespace std;

const int mod = 1e9 + 7;

int modpow(int a, long long b) {
	int ret = 1;
	while (b > 0) {
		if (b & 1) {
			ret = 1LL * ret * a % mod;
		}
		a = 1LL * a * a % mod;
		b >>= 1;
	}
	return ret;
}

int main() {
	int n;
	long long c;
	cin >> n >> c;
	
	long long foo = 0;
	vector<long long> a(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
		foo += mod - modpow(a[i], c);
	}

	vector<long long> dp(n * 2);

	dp[0] = 1;

	// doubling
	for (int ii = 0; ii < 61; ii++) {
		for (int i = 0; i < n; i++) {
			for (int j = dp.size() - 2; j >= 0; j--) {
				(dp[j + 1] += dp[j] * a[i]) %= mod;
			}
		}
		for (int j = (c & 1); j < dp.size(); j += 2) {
			dp[j / 2] = dp[j];
		}
		for (int j = dp.size() / 2; j < dp.size(); j++) {
			dp[j] = 0;
		}
		for (int i = 0; i < n; i++) {
			a[i] = a[i] * a[i] % mod;
		}
		c >>= 1;
	}

	cout << (dp[0] + foo) % mod << endl;
}