#include <cstdio>
#include <cstdlib>
#include <algorithm>
using namespace std;

#define nmax 310

int N, M, R, C, i, j, mat[nmax][nmax];
double ans, now;

int main()
{
    freopen("balans.in", "r", stdin);
    freopen("balans.out", "w", stdout);
    int i, j, k, l;
    scanf("%i %i %i %i", &N, &M, &R, &C);
    for(i = 1; i <= N; i++)
        for(j = 1; j <= M; j++)
        {
            scanf("%i", &mat[i][j]);
            mat[i + N][j] = mat[i][j + M] = mat[i + N][j + M] = mat[i][j];
        }
    for(i = 1; i <= 2 * N; i++)
        for(j = 1; j <= 2 * M; j++)
            mat[i][j] += mat[i - 1][j] + mat[i][j - 1] - mat[i - 1][j - 1];
    R = max(R, 1); C = max(C, 1);
    for(k = R; k <= N; k++)
        for(l = C; l <= M; l++)
            for(i = N + 1; i <= 2 * N; i++)
                for(j = M + 1; j <= 2 * M; j++)
                {
                    now = mat[i][j] - mat[i - k][j] - mat[i][j - l] + mat[i - k][j - l];
                    if(now > ans * k * l)
                        ans = 1.0 * now / (k * l);
                }
    printf("%.3lf",(int(ans * 1000)) / 1000.0);
    return 0;
}