#include <bits/stdc++.h>
using namespace std;
void smain();
int main() {
  ios_base::sync_with_stdio(0);
  smain();
  return 0;
}
long long n, m, a, d;
long long solve(const vector<long long> &z) {
  long long c = 0, res = 0;
  long long r = d / a + 1;
  long long left = n;
  for (auto t : z) {
    if (c >= t) continue;
    long long k = c / a;
    long long l = a * k;
    if (l <= c) l += a;
    long long g = min(left, (t - l) / a + 1);
    if (l >= t || g <= 0) {
      res += 1;
      c = min(l, t) + d;
      left = n - c / a;
      continue;
    }
    long long h = (g + r - 1) / r;
    res += h;
    left -= h * r;
    l += (h - 1) * r * a;
    c = l + d;
    if (c >= t) continue;
    res += 1;
    c = t + d;
    left = n - c / a;
  }
  left = n - c / a;
  if (left > 0) {
    long long h = (left + r - 1) / r;
    res += h;
  }
  return res;
}
void smain() {
  for (; cin >> n >> m >> a >> d;) {
    vector<long long> t(m);
    for (long long i = 0; i < m; i++) cin >> t[i];
    sort(t.begin(), t.end());
    t.resize(unique(t.begin(), t.end()) - t.begin());
    cout << solve(t) << '\n';
  }
}
