#include <bits/stdc++.h>
using namespace std;
const int N = 500;
int n, d, a, b;
bool req[N];
inline int Calc(int x, int y) {
    if (x == 0 && y == 1) return a;
    else if (y == 1) return b;
    else return 0;
}
void Solve1() {
    static int f[2][1 << 21];
    for (int i = 1; i < (1 << d + 1); ++i) f[0][i] = 1e9;
    f[0][0] = 0;
    for (int i = 0; i < 200; ++i) {
        int ni = (i + 1) & 1;
        for (int j = 0; j < (1 << d + 1); ++j) f[ni][j] = 1e9;
        // put on i+1
        for (int j = 0; j < (1 << d + 1); ++j) {
            // put on i+1
            int nf = f[i & 1][j] + Calc(j & 1, 1);
            int nj = j >> 1 | 1;
            f[ni][nj] = min(f[ni][nj], nf);
            // not put on i + 1
            if (~j >> 1 & 1) {
                int nf = f[i & 1][j] + Calc(j & 1, 0);
                int nj = j >> 1 | (req[i] << d);
                f[ni][nj] = min(f[ni][nj], nf);
            }
        }
    }
    cout << f[200 & 1][0] << endl;
}
inline void Solve2() {
    static int f[2][1 << 10];
    int num = 200 / d;
    int ans = 1e9;
    for (int st = 0; st < (1 << num + 1); st += 2) {
        bool flag = 0;
        for (int i = 0; i < num; ++i) {
            int pos = i * d;
            if (req[i] && (st >> i & 1) == 0 && (st >> i + 1 & 1) == 0) flag = 1;
        }
        if (flag) continue;
        int cur = 0;
        for (int i = 0; i < (1 << num); ++i) f[cur][i] = 1e9;
        f[cur][st & ~(1 << num)] = 0;
        for (int delta = 0; delta + 1 < d; ++delta) {
            for (int i = 0; i < num; ++i) {
                for (int j = 0; j < (1 << num); ++j) f[!cur][j] = 1e9;
                for (int j = 0; j < (1 << num); ++j) {
                    int pos = i * d + delta;
                    int nj = j | (1 << i);
                    f[!cur][nj] = min(f[!cur][nj], f[cur][j] + Calc(j >> i & 1, 1) + (delta + 1 == d - 1) * Calc(1, st >> (i + 1) & 1));
                    if (pos - d >= 0 && req[pos - d] && (j >> (i - 1) & 1) == 0) {
                        continue;
                    }
                    nj = j & ~(1 << i);
                    f[!cur][nj] = min(f[!cur][nj], f[cur][j] + Calc(j >> i & 1, 0) + (delta + 1 == d - 1) * Calc(0, st >> (i + 1) & 1));
                }
                cur ^= 1;
            }
        }
        for (int i = 0; i < (1 << num); ++i) ans = min(ans, f[cur][i]);
    }
    cout << ans << endl;
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> d >> a >> b;
    d *= 2;
    for (int i = 1, x; i <= n; ++i) {
        cin >> x;
        req[x] = 1;
    }
    if (d <= 20) {
        Solve1();
    } else {
        Solve2();
    }
    return 0;
}