#include <bits/stdc++.h>
#pragma GCC optimize ("Ofast", "unroll-loops")
using namespace std;
#define ll long long
#define int ll
#define FOR(i,a,b) for (int i = (a); i<(b); i++)
#define REP(i,n) FOR(i,0,n)
#define REP1(i,n) FOR(i,1,n+1)
#define RREP(i,n) for (int i=(n)-1; i>=0; i--)
#define f first
#define s second
#define pb push_back
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)(x.size())
#define SQ(x) (x)*(x)
#define pii pair<int, int>
#define pdd pair<double ,double>
#define pcc pair<char, char>
#define endl '\n'
//#define TOAD
#ifdef TOAD
#define bug(x) cerr<<__LINE__<<": "<<#x<<" is "<<x<<endl
#define IOS()
#else
#define bug(...)
#define IOS() ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#endif
const ll inf = (1ll<<60);
const int iinf=2147483647;
const ll mod = 998244353;
const ll maxn=3005;
const double PI=acos(-1);
ll pw(ll x, ll p, ll m=mod){
ll ret=1;
while (p>0){
if (p&1){
ret*=x;
ret%=m;
}
x*=x;
x%=m;
p>>=1;
}
return ret;
}
ll inv(ll a, ll m=mod){
return pw(a,m-2);
}
int s,t;
int val(int x){
if (x<0){
return x*t;
}
else return x*s;
}
signed main(){
IOS();
int n,q; cin>>n>>q>>s>>t;
vector<int> vc(n+1), cha(n+2);
REP(i,n+1){
cin>>vc[i];
}
int cans=0;
REP1(i,n){
cha[i]=vc[i]-vc[i-1];
if (cha[i]<0){
cans+=t*cha[i];
}
else cans+=s*cha[i];
}
REP(i,q){
int l,r,x; cin>>l>>r>>x;
int na=cha[l]+x, nb=cha[r+1]-x;
cans-=val(cha[l]);
cans+=val(na);
cha[l]=na;
if (r<n){
cans-=val(cha[r+1]);
cans+=val(nb);
cha[r+1]=nb;
}
cout<<-cans<<endl;
}
}
