#include <bits/stdc++.h>
#define pb emplace_back
#define fst first
#define scd second
#define mkp make_pair
#define mems(a, x) memset((a), (x), sizeof(a))

using namespace std;
typedef long long ll;
typedef double db;
typedef unsigned long long ull;
typedef long double ldb;
typedef pair<ll, ll> pii;

const int maxn = 2500100;
const ll mod = 1000000007;

namespace SGT {
	ll mn[maxn << 2], tag[maxn << 2];
	
	inline void init() {
		mems(mn, 0x3f);
	}
	
	inline void pushup(int x) {
		mn[x] = min(mn[x << 1], mn[x << 1 | 1]);
	}
	
	inline void pushdown(int x) {
		if (!tag[x]) {
			return;
		}
		mn[x << 1] += tag[x];
		mn[x << 1 | 1] += tag[x];
		tag[x << 1] += tag[x];
		tag[x << 1 | 1] += tag[x];
		tag[x] = 0;
	}
	
	void update(int rt, int l, int r, int ql, int qr, ll x) {
		if (ql <= l && r <= qr) {
			mn[rt] += x;
			tag[rt] += x;
			return;
		}
		pushdown(rt);
		int mid = (l + r) >> 1;
		if (ql <= mid) {
			update(rt << 1, l, mid, ql, qr, x);
		}
		if (qr > mid) {
			update(rt << 1 | 1, mid + 1, r, ql, qr, x);
		}
		pushup(rt);
	}
	
	void modify(int rt, int l, int r, int x, ll y) {
		if (l == r) {
			mn[rt] = y;
			return;
		}
		pushdown(rt);
		int mid = (l + r) >> 1;
		(x <= mid) ? modify(rt << 1, l, mid, x, y) : modify(rt << 1 | 1, mid + 1, r, x, y);
		pushup(rt);
	}
	
	ll query(int rt, int l, int r, int ql, int qr) {
		if (ql <= l && r <= qr) {
			return mn[rt];
		}
		pushdown(rt);
		int mid = (l + r) >> 1;
		ll res = 1e18;
		if (ql <= mid) {
			res = min(res, query(rt << 1, l, mid, ql, qr));
		}
		if (qr > mid) {
			res = min(res, query(rt << 1 | 1, mid + 1, r, ql, qr));
		}
		return res;
	}
}

ll f[maxn], pw[maxn];
int stk[maxn], top;

int solve(int n, int m, int* a) {
	pw[0] = 1;
	for (int i = 1; i <= n; ++i) {
		pw[i] = pw[i - 1] * 23 % mod;
	}
	ll ans = 0;
	for (int i = 1; i <= n; ++i) {
		while (top && a[stk[top]] <= a[i]) {
			SGT::update(1, 1, n, stk[top - 1] + 1, stk[top], a[i] - a[stk[top]]);
			--top;
		}
		stk[++top] = i;
		SGT::modify(1, 1, n, i, f[i - 1] + a[i]);
		f[i] = SGT::query(1, 1, n, max(1, i - m + 1), i);
		ans = (ans + f[i] % mod * pw[n - i] % mod) % mod;
	}
	return ans;
}