#include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define int long long
using namespace std;
const int maxn = 1e6 + 5;
const int base = 131313131;
const int mod = 998244353;
int n, q, k, b, a[maxn];
int pw[maxn], sum[maxn], ans[maxn];
struct node{
struct nd{
int l, r, laz;
int sum;
}tree[maxn << 2];
void pushup(int p){
tree[p].sum = (tree[p << 1].sum + tree[p << 1 | 1].sum) % mod;
}
void build(int p, int l, int r){
tree[p].l = l;tree[p].r = r;
if(l == r){
tree[p].sum = (a[l] * pw[l - 1]) % mod;
return;
}
int mid = l + r >> 1;
build(p << 1, l, mid);
build(p << 1 | 1, mid + 1, r);
pushup(p);
}
int len(int p){return tree[p].r - tree[p].l + 1;}
void add(int p, int x){
tree[p].laz += x;
tree[p].sum += sum[len(p)] * pw[tree[p].l - 1] % mod * x % mod;
}
void pushdown(int p){
int laz = tree[p].laz;
if(laz){
add(p << 1, laz);
add(p << 1 | 1, laz);
tree[p].laz = 0;
}
}
void update(int p, int l, int r, int x){
if(l <= tree[p].l && tree[p].r <= r){
add(p, x);
return;
}
pushdown(p);
int mid = tree[p].l + tree[p].r >> 1;
if(l <= mid) update(p << 1, l, r, x);
if(mid < r) update(p << 1 | 1, l, r, x);
pushup(p);
}
int query(int p, int l, int r){
if(l <= tree[p].l && tree[p].r <= r) return tree[p].sum;
pushdown(p);
int mid = tree[p].l + tree[p].r >> 1;
int sum = 0;
if(l <= mid) (sum += query(p << 1, l, r)) %= mod;
if(mid < r) (sum += query(p << 1 | 1, l, r)) %= mod;
return sum;
}
}T1;
struct node1{
struct nd{
int l, r, laz;
int sum;
}tree[maxn << 2];
void pushup(int p){
tree[p].sum = (tree[p << 1].sum + tree[p << 1 | 1].sum) % mod;
}
void build(int p, int l, int r){
tree[p].l = l;tree[p].r = r;
if(l == r){
tree[p].sum = a[l] * pw[n - l] % mod;
return;
}
int mid = l + r >> 1;
build(p << 1, l, mid);
build(p << 1 | 1, mid + 1, r);
pushup(p);
}
int len(int p){return tree[p].r - tree[p].l + 1;}
void add(int p, int x){
tree[p].laz += x;
tree[p].sum += sum[len(p)] * pw[n - tree[p].r] % mod * x % mod;
}
void pushdown(int p){
int laz = tree[p].laz;
if(laz){
add(p << 1, laz);
add(p << 1 | 1, laz);
tree[p].laz = 0;
}
}
void update(int p, int l, int r, int x){
if(l <= tree[p].l && tree[p].r <= r){
add(p, x);
return;
}
pushdown(p);
int mid = tree[p].l + tree[p].r >> 1;
if(l <= mid) update(p << 1, l, r, x);
if(mid < r) update(p << 1 | 1, l, r, x);
pushup(p);
}
int query(int p, int l, int r){
if(l <= tree[p].l && tree[p].r <= r) return tree[p].sum;
puhsdown(p);
int mid = tree[p].l + tree[p].r >> 1;
int sum = 0;
if(l <= mid) (sum += query(p << 1, l, r)) %= mod;
if(mid < r) (sum += query(p << 1 | 1, l, r)) %= mod;
return sum;
}
}T2;
bool check(int i, int mid){
int l = i - mid, r = i + mid;
int x = T1.query(1, i + 1, r) * pw[n - i + 1] % mod;
int y = T2.query(1, l, i - 1) * pw[i] % mod;
// cout << T1.query(1, i + 1, r) << " " << T2.query(1, l, i - 1) << " ";
// cout << x - y << '\n';
// cout << ans[mid] * pw[i] * pw[n - i + 1] << " ";
return (x - y + mod) % mod == (ans[mid] % mod + mod) % mod * pw[i] % mod * pw[n - i + 1] % mod;
}
signed main(){
ios::sync_with_stdio(false);
cout.tie(0);
cin.tie(0);
cin >> n >> q >> k >> b;
for(int i = 1; i <= n; i++) cin >> a[i], a[i] = (a[i] % mod + mod) % mod;
pw[0] = 1;for(int i = 1; i <= n; i++) pw[i] = pw[i - 1] * base % mod;
for(int i = 1; i <= n; i++) sum[i] = (sum[i - 1] + pw[i - 1]) % mod;
T1.build(1, 1, n);T2.build(1, 1, n);
for(int i = 1; i <= n; i++) ans[i] = (ans[i - 1] + pw[i - 1] * ((k * i + b) % mod + mod) % mod) % mod;
while(q--){
int op;cin >> op;
if(op == 1){
int l, r, v;cin >> l >> r >> v;
v = v % mod + mod;
v %= mod;
T1.update(1, l, r, v);
T2.update(1, l, r, v);
}else{
int i;cin >> i;
int l = 0, r = min(n - i, i - 1), ans = 0;
while(l <= r){
int mid = l + r >> 1;
if(check(i, mid)) ans = mid, l = mid + 1;
else r = mid - 1;
}
cout << ans << '\n';
}
}
// for(int i = 1; i <= n; i++) cout << T1.query(1, i, i) << " ";cout << '\n';
return 0;
}