#include <bits/stdc++.h>
using namespace std;

#define all(x) begin(x), end(x)
#ifdef CKISEKI
#define safe cerr << __PRETTY_FUNCTION__ << " line " << __LINE__ << " safe\n"
#define debug(a...) debug_(#a, a)
#define orange(a...) orange_(#a, a)
void debug_(const char *s, auto ...a) {
  cerr << "\e[1;32m(" << s << ") = (";
  int f = 0;
  (..., (cerr << (f++ ? ", " : "") << a));
  cerr << ")\e[0m\n";
}
void orange_(const char *s, auto L, auto R) {
  cerr << "\e[1;33m[ " << s << " ] = [ ";
  for (int f = 0; L != R; ++f)
    cerr << (f ? ", " : "") << *L++;
  cerr << " ]\e[0m\n";
}
#else
#define safe ((void)0)
#define orange(...) safe
#define debug(...) safe
#endif

template <typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, m, x, y;
  cin >> n >> m >> x >> y;
  vector<int> a(n);
  for (int &ai : a)
    cin >> ai;
  auto solve = [&](int add) {
    min_heap<pair<int64_t, int>> pq;
    pq.emplace(a[0] + add, 0);
    for (int i = 1; i < n; ++i)
      pq.emplace(a[i], i);
    for (int iter = 0; iter < m; ++iter) {
      auto [v, i] = pq.top();
      pq.pop();
      v += x;
      pq.emplace(v, i);
    }
    while (pq.top().second != 0)
      pq.pop();
    return pq.top().first;
  };
  int64_t ans = solve(y);
  int L = y - x, R = y;
  while (R - L > 1) {
    int M = (L + R) >> 1;
    int64_t v = solve(m);
    if (v >= ans)
      L = M;
    else
      R = M;
  }
  cout << max(ans, solve(L)) << '\n';
  return 0;
}