#include "peru.h"
#include <bits/stdc++.h>
using namespace std;
#define sz(x) (int)x.size()
#define all(x) x.begin() , x.end()
typedef long long ll;
const ll inf = 1e18 + 7;
const ll mod = 1e9 + 7;
struct MinStack{
stack<pair<ll,ll>>st;
ll getmin(){
return st.empty() ? inf : st.top().second;
}
void push(ll x){
st.push({x , min(x , getmin())});
}
ll pop(){
if(!st.empty()){
ll x = st.top().first;
st.pop();
return x;
}
else return -1;
}
int getsz(){
return sz(st);
}
void swap(MinStack &x){
st.swap(x.st);
}
};
struct MinDeque{
MinStack s1 , s2 , s3;
ll getmin(){
return min(s1.getmin() , s2.getmin());
}
void push_front(ll x){
s1.push(x);
}
void push_back(ll x){
s2.push(x);
}
ll pop_front(){
if(s1.getsz() == 0){
int len = s2.getsz();
for(int i = 0;i<len / 2;i++){
s3.push(s2.pop());
}
while(s2.getsz()){
s1.push(s2.pop());
}
while(s3.getsz()){
s2.push(s3.pop());
}
}
return s1.pop();
}
ll pop_back(){
if(s2.getsz() == 0){
int len = s1.getsz();
for(int i = 0;i<len / 2;i++){
s3.push(s1.pop());
}
while(s1.getsz()){
s2.push(s1.pop());
}
while(s3.getsz()){
s1.push(s3.pop());
}
}
return s2.pop();
}
};
signed solve(signed n, signed k, signed* arr){
deque<pair<int,ll>>dq;// i , dp[prev] + arr[i]
MinDeque mdq;
ll dp[n];
ll maxi = 0;
for(int i = 0;i<n;i++){
dp[i] = arr[i] + (i == 0 ? 0ll : dp[i-1]);
while(!dq.empty() and i - dq[0].first > k){
dq.pop_front();
mdq.pop_front();
}
while(!dq.empty() and arr[dq.back().first] < arr[i]){
if(sz(dq) > 1)
dp[i] = min(dp[i] , dq.back().second - arr[dq.back().first] + arr[i]);
dq.pop_back();
mdq.pop_back();
}
ll x = mdq.pop_front();
dp[i] = min(dp[i] , mdq.getmin());
if(!dq.empty()){
dp[i] = min(dp[i] , arr[dq[0].first] + dp[max(0 , i-k)]);
}
else{
dp[i] = min(dp[i] , arr[i] + dp[max(0 , i-k)]);
}
if(x != -1)mdq.push_front(x);
// cout << i << " : ";for(auto itr : dq)cout << itr.first << "," << itr.second << " ";cout << endl;
maxi = max(maxi , (ll)arr[i]);
if(i < k){
dp[i] = min(dp[i] , (ll)maxi);
}
// cout << endl;
ll prevdp = 0;
if(!dq.empty()){
prevdp = dp[dq.back().first];
}
dq.push_back({i , prevdp + arr[i]});
mdq.push_back(prevdp + arr[i]);
}
ll ans = 0 , kat = 1;
for(int i = n-1;i>=0;i--){
dp[i] %= mod;
kat %= mod;
// cout << "+= " << dp[i] << " * " << kat << endl;
ll val = (dp[i] * kat) % mod;
// cout << "val : " << val << endl;
ans = (ans + val) % mod;
kat = kat * 23ll % mod;
}
return ans;
}
signed main(){
int n,k;
cin >> n >> k;
int arr[n];
for(int i = 0;i<n;i++)cin >> arr[i];
cout << solve(n,k,arr) << endl;
}
