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//  ➡ @roadfromroi ⬅
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#include <iostream>
#include "vector"
#include "algorithm"
#include "numeric"
#include "climits"
#include "iomanip"
#include "bitset"
#include "cmath"
#include "map"
#include "deque"
#include "array"
#include "set"
#include "queue"
#include "peru.h"
#define all(x) x.begin(), x.end()
using namespace std;
typedef long long ll;
struct stackmax {
    vector<pair<int, int>> stk;
    int getval() {
        if (stk.empty())
            return 0;
        return stk.back().second;
    }
    void push(int x) {
        if (stk.empty())
            stk.push_back({x, x});
        else
            stk.push_back({x, max(x, stk.back().second)});
    }
    int pop() {
        int vl = stk.back().first;
        stk.pop_back();
        return vl;
    }
    bool empty() {
        return stk.empty();
    }
};
struct queuemax {
    stackmax a, b;
    int getval() {
        return max(a.getval(), b.getval());
    }
    void push(int x) {
        b.push(x);
    }
    void pop() {
        if (a.empty()) {
            while (!b.empty())
                a.push(b.pop());
        }
        a.pop();
    }
};
struct stackmin {
    vector<pair<ll, ll>> stk;
    ll getval() {
        if (stk.empty())
            return 1e18;
        return stk.back().second;
    }
    void push(ll x) {
        if (stk.empty())
            stk.push_back({x, x});
        else
            stk.push_back({x, min(x, stk.back().second)});
    }
    ll pop() {
        ll vl = stk.back().first;
        stk.pop_back();
        return vl;
    }
    bool empty() {
        return stk.empty();
    }
};
struct queuemin {
    stackmin a, b;
    ll getval() {
        return min(a.getval(), b.getval());
    }
    void push(ll x) {
        b.push(x);
    }
    void pop() {
        if (a.empty()) {
            while (!b.empty())
                a.push(b.pop());
        }
        a.pop();
    }
    bool empty() {
        return a.empty() and b.empty();
    }
};
int solve(int n, int k, int* v){
    vector<ll> dp(n + 1);
    dp[0] = 0;
    queuemax qmx;
    vector<int> nxtmr(n);
    for (int i = 0; i < n; ++i) {
        qmx.push(v[i]);
        if (i >= k) {
            nxtmr[i-k] = qmx.getval();
            qmx.pop();
        }
    }
    stackmin stk;
    queuemin que;
    queue<int> ind;
    for (int i = n; i < n + k; ++i) {
        nxtmr[i-k] = qmx.getval();
        qmx.pop();
    }
    int glbbeb = 0;
    vector<pair<int, pair<int, int>>> st1;
    for (int i = 0; i < n; ++i) {
        while (!st1.empty() and st1.back().first <= v[i]) {
            st1.pop_back();
            stk.pop();
        }
        int bep = 0;
        if (st1.empty()) {
            bep = max(glbbeb, i - k + 1);
        } else {
            bep = st1.back().second.second + 1;
        }
        while (nxtmr[bep] == v[i] and bep <= i) {
            que.push(v[i] + dp[bep]);
            ind.push(bep);
            bep++;
        }
        if (st1.empty())
            glbbeb = max(glbbeb, bep);
        while (!ind.empty() and ind.front() + k < i + 1) {
            ind.pop();
            que.pop();
        }
        if (bep <= i) {
            st1.push_back({v[i], {bep, i}});
            //cout << "I " << i << endl;
            //for (auto t : st1)
            //    cout << t.first << ' ' << "{" << t.second.first << ' ' << t.second.second << "}\n";
            //cout << i << ' ' << st1.back().second.first << '\n';
            stk.push(v[i] + dp[st1.back().second.first]);
        }
        dp[i + 1] = min(que.getval(), stk.getval());
    }
    ll res = 0;
    ll mod = 1e9 + 7;
    ll tomlt = 1;
    for (int i = n; i > 0; --i) {
        res += dp[i] * tomlt % mod;
        tomlt = tomlt * 23 % mod;
    }
    //for (int i = 0; i < n; ++i) {
    //    cout << dp[i + 1] << ' ';
    //}
    //cout << endl;
    return res % mod;
}
#ifdef __APPLE__
static int s[2500005];
static int n, k;
int main() {
    cin >> n >> k;
    for (int i = 0; i < n; i++) {
        cin >> s[i];
    }
    int ans = solve(n, k, s);
    cout << ans << "\n";
    return 0;
}
#endif