/* In the name of God, aka Allah */
// let this be mytemp.cpp
#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define endl '\n'
#define mk make_pair
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int N = 2e5 + 50;
ll n, q, s, t, a[N], sm[2];
ll fen[N];
ll get(int i) {
ll out = 0;
for (; i > 0; i -= i&-i) {
out += fen[i];
}
return out;
}
void upd(int i, ll x) {
for (; i <= n; i += i&-i) {
fen[i] += x;
}
}
void solve() {
cin >> n >> q >> s >> t;
s = -s;
t = -t;
for (int i = 0; i <= n; i++) {
cin >> a[i];
if (i > 0) {
sm[(a[i] > a[i-1])] += a[i]-a[i-1];
upd(i, a[i]-get(i-1));
}
}
while (q--) {
ll l, r, x;
cin >> l >> r >> x;
sm[(get(l) > get(l-1))] -= get(l)-get(l-1);
if (r < n) sm[(get(r+1) > get(r))] -= get(r+1)-get(r);
upd(l, x);
upd(r+1, -x);
sm[(get(l) > get(l-1))] += get(l)-get(l-1);
if (r < n) sm[(get(r+1) > get(r))] += get(r+1)-get(r);
cout << sm[0]*t + sm[1]*s << endl;
}
}
int main() {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
solve();
return 0;
}
