#include <iostream>
#include <vector>
#include <set>
#include <fstream>
using namespace std;

int n, m, l, b, q;
vector <int> line;
void fill (int x1, int x2) {
    for (int i = x1; i <= x2; ++i) line[i] = 1;
}

int count_0 (int x1) {
    int i = x1, count = 0;
    while (line[i] == 0) count++, i++;
    return count;
}

void find_the_longest () {
    set <int> longs; //length, coordinate;
    int i = 1, q = -1;
    while (i < m - 1) {
        if (line[i] == 0) {
            q = count_0(i);
            longs.insert(q);
            i += q;
        }
        else i++;
    }
    if (q == -1) {
        cout << 0;
        return;
    }
    auto it = longs.end();
    it--;
    cout << *it;
}

int main () {
    cin >> n >> m >> l >> b;
    line.assign(m + 1, 0);
    line[0] = 1;
    line[m] = 1;
//    fill(1, b);
//    fill(m - b, m - 1);
    for (int i = 0; i < n; i++) {
        cin >> q;
        if (q < b) fill(1, q - 1);
        else fill(q - b, q - 1);
        fill(q, q + l - 1);
        if (m - 1 - (q + l - 1) < b) fill(q + l, m - 1);
        else fill(q + l, q + l + b - 1);
    }
    //for (int i = 0; i < m; i++) cout << line[i] << ' ';
    cout << endl;
    find_the_longest();
    return 0;
}