#include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
#define N 200000
using namespace std;
int read()
{
	char c=0;
	int sum=0;
	while (c<'0'||c>'9') c=getchar();
	while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
	return sum;
}
struct reads
{
	long long sum;
	int sz,l,r;
	bool operator <= (const reads &t)const
	{
		return sum*t.sz>=t.sum*sz;
	}
};
reads dque[N+1],dque2[N+1];
reads operator + (reads a,reads b)
{
	return (reads){a.sum+b.sum,a.sz+b.sz,a.l,b.r};
}
vector<reads>p[N+1];
int n,m,lg[N+1],tong[N+1],a[N+1],top,top2;
long long s[N+1],s2[N+1],rst,ans[N+1],tans;
long long query(reads d)
{
	int ps=0;
	for (int i=lg[top];i>=0;--i)
		if (ps+(1<<i)<=top&&d<=dque[ps+(1<<i)])
			ps+=(1<<i);
	return (dque[top].r-dque[ps].r)*d.sum+s[dque[ps].r]*d.sz;
}
long long query2(reads d)
{
	int ps=0;
	for (int i=lg[top2];i>=0;--i)
		if (ps+(1<<i)<=top2&&d<=dque2[ps+(1<<i)])
			ps+=(1<<i);
	return (dque2[ps].l-dque2[top2].l)*d.sum+(s[n+1]-s[dque2[ps].l-1])*d.sz;
}
int main()
{
	reads d;
	for (int i=2;i<=N;++i) lg[i]=lg[i>>1]+1;
	n=read(),m=read(),a[n+1]=m+1;
	for (int i=1;i<=n;++i) a[i]=read();
	sort(a+1,a+n+1),dque2[0].l=n+2;
	for (int i=1;i<=n+1;++i) tong[i]=a[i]-a[i-1];
	for (int i=1;i<=n+1;++i) s[i]=s[i-1]+tong[i],s2[i]=s2[i-1]+1ll*i*tong[i];
	for (int i=1;i<=n+1;++i) ans[i]=1ll*tong[i]*n+s[i-1]*(n+1-i)+(s[n+1]-s[i])*(n+1+i)+s2[i-1]-(s2[n+1]-s2[i]);
	for (int i=n+1;i>=1;--i)
	{
		d=(reads){tong[i],1,i,i};
		while (top2&&dque2[top2]<=d) d=d+dque2[top2],p[i].push_back(dque2[top2]),top2--;
		dque2[++top2]=d;
	}
	for (int i=1;i<=n+1;++i)
	{
		if (i!=1)
		{
			d=(reads){tong[i-1],1,i-1,i-1};
			while (top&&dque[top]<=d) d=dque[top]+d,rst-=query2(dque[top]),top--;
			dque[++top]=d,rst+=query2(dque[top]);
		}
		rst-=query(dque2[top2]),--top2;
		for (int j=(int)(p[i].size())-1;j>=0;--j) dque2[++top2]=p[i][j],rst+=query(dque2[top2]);
		ans[i]-=rst;
	}
	for (int i=1;i<=n+1;++i) tans=max(tans,ans[i]);
	printf("%lld\n",tans);
	return 0;
}