#include<cstdio>
#include<cstring>
#define syy myson
using namespace std;
int n,m,t[2510],f[2510],i,j;
int min(int a,int b)
{
	return a<b?a:b;
}
int Main()
{
	freopen("cowriver.in","r",stdin);freopen("cowriver.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(i=1;i<=n;i++)
	{
		scanf("%d",&t[i]);
		t[i]+=t[i-1];
	}
	memset(f,63,sizeof(f));
	f[0]=0;
	for(i=1;i<=n;i++)for(j=1;j<=i;j++)
	  f[i]=min(f[i],f[i-j]+t[j]+2*m);
	printf("%d",f[n]-m);
	return 0;
}
int main(){;}
int syy=Main();