#include <bits/stdc++.h>

using namespace std;

const int MAXN = 150;
const int MAXM = 150;

int n, m, r, c;

int a[MAXN + 5][MAXM + 5];
long long b[2 * MAXM + 5], sp[2 * MAXM + 5];

int mod(int j) {
  if (j > n)
    j -= n;
  return j;
}

bool ok(int val) {
  for (int i = 1; i + r - 1 <= 2 * n; ++i) {
    for (int k = 1; k <= 2 * m; ++k)
      b[k] = 0;
    for (int j = i; j < i + r - 1; ++j)
      for (int k = 1; k <= m; ++k)
        b[k] = b[k + m] = b[k] + a[mod(j)][k] - val;
    for (int j = i + r - 1; j <= min(2 * n, i + n - 1); ++j) {
      for (int k = 1; k <= m; ++k)
        b[k] = b[k + m] = b[k] + a[mod(j)][k] - val;
      for (int k = 1; k < c; ++k)
        sp[k] = sp[k - 1] + b[k];
      deque<int>dq;
      for (int k = c; k < 2 * m; ++k) {
        sp[k] = sp[k - 1] + b[k];
        while (!dq.empty() && sp[dq.back()] >= sp[k - c])
          dq.pop_back();
        dq.push_back(k - c);
        long long mn = sp[dq.front()];
        if (sp[k] - mn >= 0)
          return 1;
        if (dq.front() == k - m)
          dq.pop_front();
      }
    }
  }
  return 0;
}

int main() {
  freopen("balans.in", "r", stdin);
  freopen("balans.out", "w", stdout);

  scanf("%d%d%d%d", &n, &m, &r, &c);
  for (int i = 1; i <= n; ++i)
    for (int j = 1; j <= m; ++j) {
      scanf("%d", &a[i][j]);
      a[i][j] *= 1000;
    }

  int l = 0, r = 100000000, last = 0;
  while (l <= r) {
    int med = (l + r) / 2;
    if (ok(med))
      last = med, l = med + 1;
    else
      r = med - 1;
  }


  printf("%.3f", (double)last / 1000);

  return 0;
}