#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n, q, s, t;
ll a[200020], l[200020], r[200020], x[200020];
ll segtree[800080];
void build(ll v, ll tl, ll tr)
{
if(tl==tr){segtree[v]=a[tl];}
else
{
ll tm=(tl+tr)/2;
build(v*2, tl, tm);
build(v*2+1, tm+1, tr);
segtree[v]=0;
}
}
void update(ll v, ll tl, ll tr, ll l, ll r, ll add)
{
if(l>r)return;
if(l==tl && r==tr){segtree[v]+=add;}
else
{
ll tm=(tl + tr)/2;
update(v*2, tl, tm, l, min(r, tm), add);
update(v*2+1, tm+1, tr, max(l, tm+1), r, add);
}
}
int get(ll v, ll tl, ll tr, ll pos)
{
if(tl==tr)return segtree[v];
ll tm=(tl+tr)/2;
if(pos<=tm)return segtree[v]+get(v*2, tl, tm, pos);
else return segtree[v]+get(v*2+1, tm+1, tr, pos);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cin>>n>>q>>s>>t;
for(int i=0; i<=n; i++)cin>>a[i];
for(int i=0; i<q; i++)cin>>l[i]>>r[i]>>x[i];
ll windspid=0;
for(int i=0; i<n; i++)
{
if(a[i]<a[i+1])windspid-=s*(a[i+1]-a[i]);
else windspid+=t*(a[i]-a[i+1]);
}
build(1, 0, n);
for(int i=0; i<q; i++)
{
ll d1=get(1, 0, n, l[i])-get(1, 0, n, l[i]-1), d2=get(1, 0, n, min(r[i]+1, n))-get(1, 0, n, r[i]);
update(1, 0, n, l[i], r[i], x[i]);
ll nj1=get(1, 0, n, l[i])-get(1, 0 , n, l[i]-1), nj2=get(1, 0, n, min(r[i]+1, n))-get(1, 0, n, r[i]);
if(d1>0)windspid+=s*d1;
else windspid+=t*d1;
if(nj1>0)windspid-=s*nj1;
else windspid-=t*nj1;
if(d2>0)windspid+=s*d2;
else windspid+=t*d2;
if(nj2>0)windspid-=s*nj2;
else windspid-=t*nj2;
cout<<windspid<<"\n";
}
return 0;
}
