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

template <int MOD_> struct modnum {
	static constexpr int MOD = MOD_;
	static_assert(MOD_ > 0, "MOD must be positive");

private:
	using ll = long long;

	int v;

	static int minv(int a, int m) {
		a %= m;
		assert(a);
		return a == 1 ? 1 : int(m - ll(minv(m, a)) * ll(m) / a);
	}

public:

	modnum() : v(0) {}
	modnum(ll v_) : v(int(v_ % MOD)) { if (v < 0) v += MOD; }
	explicit operator int() const { return v; }
	friend std::ostream& operator << (std::ostream& out, const modnum& n) { return out << int(n); }
	friend std::istream& operator >> (std::istream& in, modnum& n) { ll v_; in >> v_; n = modnum(v_); return in; }

	friend bool operator == (const modnum& a, const modnum& b) { return a.v == b.v; }
	friend bool operator != (const modnum& a, const modnum& b) { return a.v != b.v; }

	modnum inv() const {
		modnum res;
		res.v = minv(v, MOD);
		return res;
	}
	friend modnum inv(const modnum& m) { return m.inv(); }
	modnum neg() const {
		modnum res;
		res.v = v ? MOD-v : 0;
		return res;
	}
	friend modnum neg(const modnum& m) { return m.neg(); }

	modnum operator- () const {
		return neg();
	}
	modnum operator+ () const {
		return modnum(*this);
	}

	modnum& operator ++ () {
		v ++;
		if (v == MOD) v = 0;
		return *this;
	}
	modnum& operator -- () {
		if (v == 0) v = MOD;
		v --;
		return *this;
	}
	modnum& operator += (const modnum& o) {
		v += o.v;
		if (v >= MOD) v -= MOD;
		return *this;
	}
	modnum& operator -= (const modnum& o) {
		v -= o.v;
		if (v < 0) v += MOD;
		return *this;
	}
	modnum& operator *= (const modnum& o) {
		v = int(ll(v) * ll(o.v) % MOD);
		return *this;
	}
	modnum& operator /= (const modnum& o) {
		return *this *= o.inv();
	}

	friend modnum operator ++ (modnum& a, int) { modnum r = a; ++a; return r; }
	friend modnum operator -- (modnum& a, int) { modnum r = a; --a; return r; }
	friend modnum operator + (const modnum& a, const modnum& b) { return modnum(a) += b; }
	friend modnum operator - (const modnum& a, const modnum& b) { return modnum(a) -= b; }
	friend modnum operator * (const modnum& a, const modnum& b) { return modnum(a) *= b; }
	friend modnum operator / (const modnum& a, const modnum& b) { return modnum(a) /= b; }
};

template <typename T> T pow(T a, long long b) {
	assert(b >= 0);
	T r = 1; while (b) { if (b & 1) r *= a; b >>= 1; a *= a; } return r;
}

using num = modnum<int(1e9)+7>;

template <typename K, typename V>
using hash_map = unordered_map<K, V>;

const int MAXN = 1.1e5;
const int M = 1e9;
int N, K;
int A[MAXN];
int B[MAXN];

num go(int v, const vector<int>& inds, const vector<int>& intervals) {
	int L = int(intervals.size());
	vector<num> res(L+1); res[0] = 1;
	num totVal = res[0];

	num mult = 1;
	num imult = 1;
	num r = M-v;
	num inv = (r == 0 ? num(1) : r.inv());

	int lo = 0, hi = 1;
	for (int i : inds) {
		while (hi <= L && intervals[hi-1] <= i) {
			hi++;
		}
		while (intervals[lo]+K <= i) {
			totVal -= res[lo] * mult;
			lo++;
		}

		num curVal = totVal;
		mult *= r;
		imult *= inv;
		totVal *= r;
		totVal += curVal;
		res[hi-1] += curVal * imult;
	}

	return res.back() * mult;
}

int main() {
	ios::sync_with_stdio(0), cin.tie(0);

	cin >> N >> K;
	for (int i = 0; i < N-K+1; i++) {
		cin >> A[i];
	}

	// set max
	{
		deque<pair<int, int>> dq;
		for (int i = 0; i < N; i++) {
			if (i < N-K+1) {
				pair<int, int> val(A[i], i);
				while (!dq.empty() && dq.back() < val) {
					dq.pop_back();
				}
				dq.push_back(val);
			}
			if (dq.front().second == i-K) {
				dq.pop_front();
			}
			assert(!dq.empty());
			B[i] = dq.front().first;
		}

		//for (int i = 0; i < N; i++) { cerr << B[i] << " \n"[i+1==N]; }
	}

	hash_map<int, vector<int>> inds;
	hash_map<int, vector<int>> intervals; // lefts
	for (int i = 0; i < N; i++) {
		inds[B[i]].push_back(i);
	}
	for (int i = 0; i < N-K+1; i++) {
		intervals[A[i]].push_back(i);
	}

	num ans = 1;
	for (auto it : intervals) {
		int v = it.first;
		ans *= go(v, inds[v], it.second);
	}
	cout << ans << '\n';

	return 0;
}