#include <iostream>
#include <cstdio>
using namespace std;
const int maxn = 305;
int M[maxn][maxn];
long long sp[maxn][maxn];
int n, m;
void calc()
{
    for(int i = 1; i <= n * 2; i++)
        for(int j = 1; j <= m * 2; j++)
            sp[i][j] = sp[i - 1][j] + sp[i][j - 1] - sp[i - 1][j - 1] + M[i][j];
}

long long get_sum(int x1, int y1, int x2, int y2)
{
    return sp[x2][y2] - sp[x1 - 1][y2] - sp[x2][y1 - 1] + sp[x1 - 1][y1 - 1];
}

int get_dim(int x1, int y1, int x2, int y2)
{
    return (x2 - x1 + 1) * (y2 - y1 + 1);
}

int main()
{
    freopen("balans.in", "r", stdin);
    freopen("balans.out", "w", stdout);
    int r, c;
    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", &M[i][j]);
            M[i][j + m] = M[i][j];
            M[i + n][j] = M[i][j];
            M[i + n][j + m] = M[i][j];
        }
    }
    calc();
    double mx = 0;
    for(int i = 1; i <= n; i++)
    {
        for(int j = 1; j <= m; j++)
        {
            for(int p = i + r - 1; p <= i + n - 1; p++)
            {
                for(int q = j + c - 1; q <= j + m - 1; q++)
                {
                    double x = get_sum(i, j, p, q);
                    mx = max(mx, (x / get_dim(i, j, p, q)));
                }
            }
        }
    }
    printf("%.3f\n", mx);
    return 0;
}