#include<bits/stdc++.h>
#define COGS
using namespace std;
const int maxn=1010;
int cost[20*maxn],f[20*maxn];
int n,m,temp;
inline void in(){
	#ifdef COGS
	freopen("cowriver.in","r",stdin);
	freopen("cowriver.out","w",stdout);
	#endif
	scanf("%d%d",&n,&m);
	for (int i=1;i<=n;i++){
		scanf("%d",&temp);
		cost[i]+=cost[i-1]+temp;
		f[i]=1e9;
	}
} 
inline void dp(){
	for (int v=1;v<=n;v++){
		for (int j=v;j>=1;j--){
			f[v]=min(f[v],f[v-j]+cost[j]+2*m);
		}
	}
}
inline void p(){
	printf("%d",f[n]-m);
}
int Main(){
	in();
	dp();
	p();
	return 0;
}
int main(){;}
int xlm=Main();