#include<bits/stdc++.h> #define Rf(i,a,b) for(int i=(a);i<=(b);i++) #define Rb(i,a,b) for(int i=(a);i>=(b);i--) #define ll long long #define PII pair<int,int> #define mpx make_pair #define int ll using namespace std; const int S=1e7+10,N=1e5+10,V=120; int n,c;int a[N];int v=0; struct nd{ int id,vl; bool operator<(const nd &b){ return vl<b.vl; } }tmp[N]; int fa[N],val[N];ll w[N];int len[N]; int find(int x){ if(x==fa[x]) return x; return fa[x]=find(fa[x]); } void merge(int x,int y){ int X=find(x),Y=find(y); fa[X]=Y;len[Y]+=len[X];w[Y]+=w[X]; } signed main(){ //freopen("seq.in","r",stdin);freopen("1.out","w",stdout); cin>>n>>c;Rf(i,1,n) cin>>a[i],fa[i]=i,w[i]=1,len[i]=1; Rf(i,1,n) tmp[i]=(nd){i,a[i]},val[i]=a[i];sort(tmp+1,tmp+n+1); ll ans=0;Rf(i,2,n) ans+=1ll*abs(a[i]-a[i-1])*c; Rf(i,2,n) if(val[i]==val[i-1]) merge(i,i-1); Rf(i,1,n){ int ps=tmp[i].id; int lp=find(ps)-1,rp=find(ps)+len[find(ps)]; int to=1e9+10;int cnt=0; if(lp>=1){ to=min(to,val[find(lp)]);cnt++; }if(rp<=n){ to=min(to,val[find(rp)]);cnt++; }if(to>1e6+30) break; int now=val[find(ps)];if(to<now) continue; int cost=cnt*c;if(w[find(ps)]<=cnt*c){ int cntlen=(cost-w[find(ps)])/len[find(ps)]; cntlen=cntlen/2*2;int D=cntlen/2; D=min(to-now,D+1); ll pay=D*w[find(ps)]+D*(D-1)*len[find(ps)]-cost*D; ans+=pay; val[find(ps)]+=D;w[find(ps)]+=2*D*len[find(ps)]; } if(lp>=1){ if(val[find(ps)]==val[find(lp)]) merge(ps,lp); } if(rp<=n){ if(val[find(ps)]==val[find(rp)]) merge(rp,ps); } }cout<<ans; return 0; }