#include "peru.h"
#include<bits/stdc++.h>
using namespace std;
namespace my_std{
	#define ll long long
	#define bl bool
	ll my_pow(ll a,ll b,ll mod){
		ll res=1;
		if(!b) return 1;
		while(b){
			if(b&1) res=(res*a)%mod;
			a=(a*a)%mod;
			b>>=1;
		}
		return res;
	}
	ll qpow(ll a,ll b){
		ll res=1;
		if(!b) return 1;
		while(b){
			if(b&1) res*=a;
			a*=a;
			b>>=1;
		}
		return res;
	}
	#define db double
	#define pf printf
	#define pc putchar
	#define fr(i,x,y) for(register ll i=(x);i<=(y);i++)
	#define pfr(i,x,y) for(register ll i=(x);i>=(y);i--)
	#define go(u) for(ll i=head[u];i;i=e[i].nxt)
	#define enter pc('\n')
	#define space pc(' ')
	#define fir first
	#define sec second
	#define MP make_pair
	#define il inline
	#define inf 1e18
	#define random(x) rand()*rand()%(x)
	#define inv(a,mod) my_pow((a),(mod-2),(mod))
	il ll read(){
		ll sum=0,f=1;
		char ch=0;
		while(!isdigit(ch)){
			if(ch=='-') f=-1;
			ch=getchar();
		}
		while(isdigit(ch)){
			sum=sum*10+(ch^48);
			ch=getchar();
		}
		return sum*f;
	}
	il void write(ll x){
		if(x<0){
			x=-x;
			pc('-');
		}
		if(x>9) write(x/10);
		pc(x%10+'0');
	}
	il void writeln(ll x){
		write(x);
		enter;
	}
	il void writesp(ll x){
		write(x);
		space;
	}
}
using namespace my_std;
#define mod 1000000007
ll f[2500025],q[2500025],l=1,r=0;
struct node{
	ll q[2500025],l=1,r=0,mid=1,pre[2500025],suf[2500025],val[2500025];
	il void remake(){
		if(l>r) return;
		fr(i,l-1,r+1) pre[i]=suf[i]=inf;
		mid=(l+r)>>1;
		pfr(i,mid,l) pre[i]=min(pre[i+1],val[i]);
		fr(i,mid+1,r) suf[i]=min(suf[i-1],val[i]);
	}
	il void dell(){
		l++;
		if(l>mid) remake();
	}
	il void delr(){
		r--;
		if(r<mid) remake();
	}
	il void addr(ll v){
		val[++r]=v;
		if(l==r) remake();
		else suf[r]=min(suf[r-1],v);
	}
	il void mdfl(ll v){
		val[l]=v;
		pre[l]=min(pre[l+1],val[l]);
	}
	il ll query(){
		return min(pre[l],suf[r]);
	}
}T;
int solve(int n,int k,int* a){
	pfr(i,n,1) a[i]=a[i-1];
	fr(i,1,n){
		f[i]=inf;
		while(l<=r&&q[l]<=(i-k)){
			l++;
			T.dell();
		}
		while(l<=r&&a[q[r]]<=a[i]){
			r--;
			T.delr();
		}
		q[++r]=i;
		q[l-1]=max(0ll,i-k);
		T.addr(f[q[r-1]]+a[i]);
		T.mdfl(f[q[l-1]]+a[q[l]]);
		f[i]=T.query();
	}
	ll ans=0,now=1;
	pfr(i,n,1){
		ans=(ans+now*f[i]%mod)%mod;
		now=now*23ll%mod;
	}
	return ans;
}