#include <bits/stdc++.h>
#ifdef DEBUG
#include "../templates/debug.h"
#else
#define deb(x...)
#endif
using namespace std;
#define int long long
const int N = 2e5 + 10;
int n, q, S, T, t[4*N], a[N];
void build(int v, int tl, int tr){
if(tl == tr)t[v] = a[tl];
else{
int tm = (tl + tr)/2;
build(v*2, tl, tm);
build(v*2 + 1, tm + 1, tr);
}
}
void update(int l, int r, int x, int v, int tl, int tr){
if(l > r)return;
else if(l == tl && r == tr)t[v] += x;
else{
int tm = (tl + tr)/2;
update(l, min(tm, r), x, v*2, tl, tm);
update(max(l, tm + 1), r, x, v*2+1,tm+1,tr);
}
}
int query(int x, int v, int tl, int tr){
if(tl == tr)return t[v];
else{
int tm = (tl + tr)/2;
if(x <= tm)return t[v] + query(x, v*2,tl,tm);
else return t[v] + query(x,v*2+1,tm+1,tr);
}
}
signed main() {
iostream::sync_with_stdio(false);
cin.tie(nullptr);cout.tie(nullptr);
cin >> n >> q >> S >> T;
for(int i = 0;i<=n;i++)cin >> a[i];
int calc = 0;
auto dd = [&](int a, int b, int sign){
if(b > a)calc -= sign*(b - a)*S;
else calc += sign*(a - b)*T;
};
for(int i = 0;i<n;i++){
dd(a[i], a[i + 1], 1);
}
build(1, 0, n);
while(q--){
int l, r;cin >> l >> r;
int x;cin >> x;
int f1 = query(l - 1, 1, 0, n), f2 = query(l, 1, 0, n);
int s1 = query(r, 1, 0, n), s2 = query(min(r + 1, n), 1, 0, n);
dd(f1, f2, -1);dd(s1, s2, -1);
update(l, r, x, 1, 0, n);
f1 = query(l - 1, 1, 0, n), f2 = query(l, 1, 0, n);
s1 = query(r, 1, 0, n), s2 = query(min(r + 1, n), 1, 0, n);
dd(f1, f2, 1);dd(s1, s2, 1);
cout << calc << "\n";
}
}
