#include<bits/stdc++.h>
using namespace std;
#define N 5005
#define fr first
#define se second
#define ls u<<1
#define rs u<<1|1
#define M 10000005
#define p 998244353
#define pb push_back
#define ll long long
#define inf 0x3f3f3f3f
#define pii pair<int,int>
int n,a[N],d;
ll calc(int l,int r){
    ll ans=0;
    for(int i=1;i<n;i++){
        int L=min(a[i],a[i+1]),R=max(a[i],a[i+1]);
        if(max(l,L)<=min(r,R))
            ans+=min(r,R)-max(l,L);
    }
    return ans;
}
int main(){
    freopen("ans.in","r",stdin);
    scanf("%d%d",&n,&d);
    for(int i=1;i<=n;i++)scanf("%d",&a[i]);
    ll ans=0;
    for(int i=1,l,r;i<n;i++){
        l=min(a[i],a[i+1]),r=max(a[i],a[i+1]);
        ans=max({ans,calc(l,l+d),calc(r-d,r)});
    }
    printf("%lld\n",ans);
}