#include<bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e6 + 66;
ll f[N];
void upd(int pos, ll v) {
while (pos < N) {
f[pos] += v;
pos |= pos + 1;
}
}
ll gt(int pos) {
ll r = 0;
while (pos >= 0) {
r += f[pos];
pos &= pos + 1;
pos--;
}
return r;
}
ll a[N], S, T, All;
int n, q;
ll get(int i) {
if (i >= n || i < 0) return 0;
if (a[i] + gt(i) < a[i + 1] + gt(i + 1)) {
return (a[i] + gt(i) - a[i + 1] - gt(i + 1)) * S;
} else {
return (a[i] + gt(i) - a[i + 1] - gt(i + 1)) * T;
}
}
int main() {
ios_base::sync_with_stdio(0);
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 < n ; ++ i) {
All += get(i);
}
while (q--) {
int l, r; ll x;
cin >> l >> r >> x;
All -= get(l-1);
All -= get(r);
upd(l, x);
upd(r+1,-x);
All += get(l-1);
All += get(r);
cout << All << "\n";
}
}
