#include "bits/stdc++.h"
#ifdef DEBUG
#include "algo/debug.hpp"
#else
#define dbg(...)
#define dbgm(...)
#endif
using namespace std;
typedef long long ll;
typedef unsigned int ui;
typedef unsigned long long ull;
typedef pair<int, int> pi;
typedef pair<ll, ll> pll;
// using u128 = __uint128_t;
// using i128 = __int128;
const int mod = 1000000007;
const int N = 205;
const int D = 1 << 10;
const int LOG = 20;
const int inf = 1e9;
const double eps = 1e-11;
int p[N], f[D * D], nf[D * D], g[D][D], ng[D][D];
int n, m, qq, d, a, b, mx = 0;
void solve1() {
    int k = 1 << d, l = k / 2;
    fill(f, f + D * D, inf);
    f[0] = 0;
    for (int i = 0; i < mx; i++) {
        swap(f, nf);
        fill(f, f + D * D, inf);
        for (int mask = 0; mask < k; mask++) {
            bool move = 0;
            if (i >= d) {
                if (!(mask & 1) && p[i - d]) move = 1;
            }
            
            int x = (mask >> d - 1) ? b : a;
            int msk = mask >> 1;
            if (!move) f[msk] = min(f[msk], nf[mask]);
            f[msk | l] = min(f[msk | l], nf[mask] + x);
        }
    }
    
    int out = inf;
    for (int mask = 0; mask < k; mask++) {
        out = min(out, f[mask]);
    }
    
    cout << out << "\n";
}

void solve2() {
    int s = (mx + d - 1) / d, k = 1 << s;
    // dbgm(s, k, mx);
    for (int i = 0; i < D; i++) {
        fill(g[i], g[i] + D, inf);
    }
    
    g[0][0] = 0;
    for (int i = 0; i < d; i++) {
        for (int j = 0; j * d + i < mx; j++) {
            swap(g, ng);
            for (int x = 0; x < D; x++) {
                fill(g[x], g[x] + D, inf);
            }
            
            int pos = j * d + i;
            for (int mask = 0; mask < k; mask++) {
                for (int smask = 0; smask < k; smask++) {
                    bool move = 0;
                    if (j) {
                        if (!((mask >> j - 1) & 1) && p[pos - d]) move = 1;
                    }
                    
                    int bit = (mask >> j) & 1, x = bit ? b : a;
                    if (i == d - 1 && pos < mx - 1 && ((smask >> j + 1) & 1)) {
                        x += b - a;
                    }
                    
                    // dbgm(i, j, mask, smask, move, x, pos, ng[mask][smask]);
                    int bv = (1 << j), v = bv * bit, msk = mask ^ v;
                    int smsk = i == 0 ? msk : smask;
                    if (!move) {
                        g[msk][smsk] = min(g[msk][smsk], ng[mask][smask]);
                    }
                    
                    msk ^= bv;
                    if (i == 0) smsk ^= bv;
                    g[msk][smsk] = min(g[msk][smsk], ng[mask][smask] + x);
                }
            }
            
            // dbgm(i, j, x);
            // dbg(g);
        }
    }
    
    int out = inf;
    for (int mask = 0; mask < k; mask++) {
        for (int smask = 0; smask < k; smask++) {
            out = min(out, g[mask][smask]);
        }
    }
    
    cout << out << "\n";
}

void solve() {
    cin >> n >> d >> a >> b;
    b = min(a, b);
    for (int i = 0; i < n; i++) {
        int x;
        cin >> x;
        mx = max(mx, x);
        x--;
        p[x] = 1;
    }
    
    d *= 2, mx += d;
    if (d <= 0) solve1();
    else solve2();
}

int32_t main() {
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    solve();
}