#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = a; i<=b ; i++)
#define FORD(i, a, b) for (int i = a; i>=b; i--)
#define REP(i, a) for (int i = 0; i<a; i++)
#define N 100100
#define pp pair<int, int>
#define IO cin.tie(NULL);cout.tie(NULL);
template<typename T> inline void read(T &x) {
char c;
bool neg = false;
while (!isdigit(c = getchar()) && c != '-');
x = 0;
if (c == '-') {
neg = true;
c = getchar();
}
do {
x = x * 10 + c - '0';
} while (isdigit(c = getchar()));
if (neg) x = -x;
}
template<typename T> inline void write(T x) {
if (x < 0) {
putchar('-');
write(-x);
return;
}
if (x < 10) {
putchar(char(x + 48));
}
else {
write(x/10);
putchar(char(48 + x%10));
}
}
template<typename T> inline void writeln(T x) {
write(x);
putchar('\n');
}
using namespace std;
int n, q;
vector<long long> a, b;
long long neg, po, s, t;
void Up(int u, int x) {
if (b[u] < 0) neg -= b[u];
else po -= b[u];
b[u] += x;
if (b[u] < 0) neg += b[u];
else po += b[u];
}
int main() {
IO;
read(n);read(q);read(s);read(t);
a.resize(n + 5);
b.resize(n + 5);
REP(i, n + 1) read(a[i]);
FOR(i, 1, n) b[i] = 0;
int l, r, x;
neg = po = 0;
FOR(i, 1, n) Up(i, a[i] - a[i - 1]);
while (q--) {
read(l);read(r);read(x);
Up(l, x);
if (r != n) Up(r + 1, -x);
long long ans = -neg * t - po * s;
writeln(ans);
}
}
