#include <algorithm>
#include <iostream>
#include <fstream>
#include <deque>

using namespace std;

ifstream in("balans.in");
ofstream out("balans.out");

typedef long long ll;

const int NMAX = 150;
const int NORM = 1e3;

int n, m, r, c;
ll res;
ll sum[1 + 2 * NMAX];
ll a[1 + 2 * NMAX][1 + 2 * NMAX];
ll sp[1 + 2 * NMAX][1 + 2 * NMAX];
ll maxx;

deque < int > dq;

bool ok(int x) {
  fill(sum, sum + 2 * NMAX + 1, 0);
  ll mx;

  for(int l1 = 1; l1 <= n; l1++) {
    for(int l2 = l1 + r - 1; l2 <= l1 + n - 1; l2++) {
      for(int i = 1; i <= 2 * m; i++)
        sum[i] = sum[i - 1] + sp[l2][i] - sp[l1 - 1][i] - (l2 - l1 + 1) * x;

      dq.clear();
      mx = sum[c];
      dq.push_back(1);

      for(int i = c + 1; i <= 2 * m; i++) {
        while(!dq.empty() && dq.back() + m - 1 < i)
          dq.pop_back();

        while(!dq.empty() && sum[i] - sum[dq.front() - 1] <= sum[i] - sum[i - c])
          dq.pop_front();
        dq.push_front(i - c + 1);
        mx = max(mx, sum[i] - sum[dq.back() - 1]);
        if(m < dq.back())
          break;
      }

      if(0 <= mx)
        return true;
    }
  }

  return false;
}

int main()
{
  in >> n >> m >> r >> c;
  for(int i = 1; i <= n; i++) {
    for(int j = 1; j <= m; j++) {
      in >> a[i][j];
      a[i][j] *= NORM;
      maxx = max(maxx, a[i][j]);
    }
  }

  for(int i = 1; i <= n; i++)
    for(int j = 1; j <= m; j++)
      a[i + n][j] = a[i][j + m] = a[i + n][j + m] = a[i][j];

  for(int i = 1; i <= 2 * n; i++)
    for(int j = 1; j <= 2 * m; j++)
      sp[i][j] = sp[i - 1][j] + a[i][j];

  int from = 0, to = maxx;
  while(from <= to) {
    ll mid = from + (to - from) / 2;
    if(ok(mid) == true) {
      res = mid;
      from = mid + 1;
    } else
      to = mid - 1;
  }

  out << res / NORM << '.' << res % NORM << '\n';

  in.close();
  out.close();
  return 0;
}