#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int n,q;
ll s,t,c[200010],fen[200010],ans;
void update(int x, int val) {
while (x<=n+5) {
fen[x]+=val;
x+=(x&-x);
}
}
ll find(int x) {
ll sum=c[x];
while (x) {
sum+=fen[x];
x-=(x&-x);
}
return sum;
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>n>>q>>s>>t;
for (int i=1; i<=n+1; ++i) {
cin>>c[i];
if (i>1) {
if (c[i]>c[i-1]) ans-=(s*(c[i]-c[i-1]));
else ans+=(t*(c[i-1]-c[i]));
}
}
while (q--) {
int a,b; ll val;
cin>>a>>b>>val;
++a; ++b;
if (a!=1) {
ll pa=find(a-1), ha=find(a);
if (pa<ha) ans+=s*(ha-pa);
else ans-=t*(pa-ha);
ha+=val;
if (pa<ha) ans-=s*(ha-pa);
else ans+=t*(pa-ha);
}
if (b!=n+1) {
ll pb=find(b+1), hb=find(b);
if (hb<pb) ans+=s*(pb-hb);
else ans-=t*(hb-pb);
hb+=val;
if (hb<pb) ans-=s*(pb-hb);
else ans+=t*(hb-pb);
}
update(a,val);
update(b+1,-val);
cout<<ans<<"\n";
}
}
