#include <iostream>
#include <iomanip>
#include <cstdio>
 
using namespace std;
 
typedef long long ll;
const int N = 300 + 7;
int n, m, x, y;
int a[N][N];
ll c[N][N];
ll mn[N];
 
bool ok(int num) {
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      c[i][j] = a[i][j] - num + c[i][j - 1];
    }
  }
 
  for (int l = 1; l <= m; l++) {
    for (int r = l + y - 1; r <= min(m, r + 10); r++) {
      ll cur = 0;
      for (int i = 1; i <= n; i++) {
        cur += c[i][r] - c[i][l - 1];
        mn[i] = min(mn[i - 1], cur);
        if (i >= x && cur - mn[i - x] >= 0LL) {
          return 1;
        }
      }
    }
  }
  return 0;
}
 
int main() {
  freopen ("balans.in", "r", stdin);
  freopen ("balans.out", "w", stdout);
 
  cin >> n >> m >> x >> y;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      cin >> a[i][j];
      a[i][j] *= 1000;
      a[i + n][j] = a[i][j + m] = a[i + n][j + m] = a[i][j];
    }
  }
 
  n *= 2;
  m *= 2;
 
  int l = 0, r = 100000000, ans = 0;
  while (l <= r) {
    int mid = (l + r) / 2;
    if (ok(mid)) {
      ans = mid;
      l = mid + 1;
    } else {
      r = mid - 1;
    }
  }
 
  cout << fixed << setprecision(3) << ans / 1000.0 << "\n";
 
  return 0;
}