#include <fstream>
#include <deque>
#include <iomanip>

using namespace std;

int N, M, R, C;
long long mat[311][311];
long long v[311];
deque <pair <long long, int> > Dq;

void Citire ()
{
    ifstream fin ("balans.in");
    fin >> N >> M >> R >> C;
    for (int i = 1; i <= N; i++)
    {
        for (int j = 1; j <= M; j++)
        {
            fin >> mat[i][j];
            mat[i][j] *= 1000;
            mat[i + N][j] = mat[i][j];
            mat[i][j + M] = mat[i][j];
            mat[i + N][j + M] = mat[i][j];
        }
    }
    fin.close ();
    for (int i = 1; i <= (N << 1); i++)
        for (int j = 1; j <= (M << 1); j++)
            mat[i][j] += mat[i - 1][j];
}

int Good (int a, int b, int K)
{
    for (int i = 1; i <= (M << 1); i++)
        v[i] = v[i - 1] + mat[b][i] - mat[a - 1][i] - 1LL * (b - a + 1) * K;
    Dq.clear ();
    for (int i = C; i <= (M << 1); i++)
    {
        while (!Dq.empty () && i - Dq.front ().second > M) Dq.pop_front ();
        while (!Dq.empty () && Dq.back ().first > v[i - C]) Dq.pop_back ();
        Dq.push_back (make_pair (v[i - C], i - C));
        if (v[i] - Dq.front ().first >= 0) return 1;
    }
    return 0;
}

int B_Search (int a, int b)
{
    int val = 0;
    for (int step = 1 << 30; step; step >>= 1)
        if (Good (a, b, step + val)) val += step;
    return val;
}

int Business ()
{
    int Ans = -1;
    for (int a = 1; a <= N; a++)
    {
        for (int b = a + R - 1; b < a + N; b++)
        {
            int local = B_Search (a, b);
            if (local > Ans) Ans = local;
        }
    }
    return Ans;
}

void Scriere ()
{
    ofstream fout ("balans.out");
    int Ans = Business ();
    int zec = Ans % 1000;
    fout << Ans / 1000 << ".";
    if (zec < 10) fout << "00";
    else if (zec < 100) fout << "0";
    fout << zec;
    fout.close ();
}

int main ()
{
    Citire ();
    Scriere ();
    return 0;
}