#include <bits/stdc++.h> 

using namespace std; 

typedef long long ll;

const int N = 25 * 1e2 + 10;
const ll MOD = 1e9 + 7;

int dp[N];

int add(int a, int b){
	if(a + b < 0) return a + b + N;
	if(a + b >= N) return a + b - N;
	return a + b;
}

ll MODadd(ll a, ll b){
	return (a + b) % MOD;
}

ll MODmult(ll a, ll b){
	return a * b % MOD;
}

struct elem{
	int val, maxi, ind;
	elem(){
		val = 0;
		maxi = 0;
		ind = 0;
	};
};

struct monostack{
	elem arr[N];
	int ind = 0;
	void push(elem x){
		if(ind) x.val = min(x.val, arr[ind - 1].val);
		arr[ind] = x;
		ind++;
	};
	elem pop(){
		if(ind){
			ind--;
			return arr[ind];
		}
		assert(false);
		return arr[ind];
	};
	elem front(){
		if(ind) return arr[ind - 1];
		assert(false);
		return arr[ind];
	};
	int size(){
		return ind;
	};
	void clear(){
		ind = 0;
	};
};

struct monodeck{
	monostack l, r;
	elem arr[N];
	int L = 0, R = 1;
	void build(){
		if(l.size() > 0 && r.size() > 0) return;
		int mi = (L + R) >> 1;
		if(L > R) mi = (L - N + R) >> 1;
		l.clear();
		r.clear();
		for(int i = mi; i != L; i = add(i, -1)){
			assert(i >= 0);
			l.push(arr[i]);
		} 
		for(int i = mi + 1; i != R; i = add(i, 1)){
			assert(i < N);
			r.push(arr[i]);
		} 
	}
	void push_front(elem x){
		arr[L] = x;
		l.push(x);
		L = add(L, -1);
		build();
	};
	void push_back(elem x){
		arr[R] = x;
		r.push(x);
		R = add(R, 1);
		build();
	};
	elem pop_front(){
		if(l.size() == 0) swap(l, r);
		L = add(L, 1);
		elem ret = l.pop();
		build();
		return ret;
	};
	elem pop_back(){
		if(r.size() == 0) swap(l, r);
		R = add(R, -1);
		elem ret = r.pop();
		build();
		return ret;
	};
	elem front(){
		return arr[add(L, 1)];
	};
	elem back(){
		return arr[add(R, -1)];
	};
	int size(){
		return l.size() + r.size();
	};
};

ll DP(int x){
	if(x < 0) return 0;
	return dp[x];
}

int solve(int n, int k, int* arr){
	elem res, p; 
	monodeck s;
	dp[0] = arr[0];
	p.val = arr[0];
	p.maxi = arr[0];
	p.ind = 0;
	s.push_back(p);
	for(int i = 1; i < n; i++){
		if(i >= k){
			res = s.front();
			if(res.ind == i - k) res = s.pop_front();
			p.val = dp[i - k] + res.maxi;
			p.maxi = res.maxi;
			p.ind = i - k + 1;
			if(res.ind != i - k + 1) s.push_front(p);
		}
		bool del = false;
		while(s.size() > 0 && s.back().maxi < arr[i]){
			res = s.pop_back();
			del = true;
		}
		if(del){
			p.val = DP(res.ind - 1) + arr[i];
			p.maxi = arr[i];
			p.ind = res.ind;
			s.push_back(p);
		}
		p.val = arr[i] + dp[i - 1];
		p.maxi = arr[i];
		p.ind = i;
		s.push_back(p);
		dp[i] = min(s.front().val, s.back().val);
		//printf("%d, ", dp[i]);
	}
	ll ans = 0;
	ll c = 1;
	for(int i = n - 1; i >= 0; i--){
		ans = MODadd(ans, MODmult(dp[i], c));
		c = MODmult(c, 23);
	}
	return ans;
}

int main(){
	int n, k;
	scanf("%d%d", &n, &k);
	int arr[n];
	for(int i = 0; i < n; i++) scanf("%d", &arr[i]);
	printf("ans: %lld\n", solve(n, k, arr));
	return 0;
}

implementer.cpp: In function ‘char nextch()’:
implementer.cpp:15:31: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   15 |     if (pos == BUF_SIZE) fread(buf, BUF_SIZE, 1, fin), pos = 0;
      |                          ~~~~~^~~~~~~~~~~~~~~~~~~~~~~
answer.code: In function ‘int main()’:
answer.code:174:25: warning: format ‘%lld’ expects argument of type ‘long long int’, but argument 2 has type ‘int’ [-Wformat=]
  174 |         printf("ans: %lld\n", solve(n, k, arr));
      |                      ~~~^     ~~~~~~~~~~~~~~~~
      |                         |          |
      |                         |          int
      |                         long long int
      |                      %d
answer.code:171:14: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  171 |         scanf("%d%d", &n, &k);
      |         ~~~~~^~~~~~~~~~~~~~~~
answer.code:173:41: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  173 |         for(int i = 0; i < n; i++) scanf("%d", &arr[i]);
      |                                    ~~~~~^~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/ccVT2yfp.o: in function `main':
answer.code:(.text.startup+0x0): multiple definition of `main'; /tmp/ccpIA1km.o:implementer.cpp:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status