#include <cstring>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <deque>

using namespace std;

const int SIZE = 301;
const double eps = 0.00001;

int N, M, R, C;
int A[SIZE][SIZE];
double S[SIZE][SIZE];
deque<int> Dl, Dr[SIZE];

bool canget(double X)
{
	memset(S, 0, sizeof(S));
	for (int i = 1; i <= N * 2; ++i)
		for (int j = 1; j <= M * 2; ++j)
			S[i][j] = S[i - 1][j] + S[i][j - 1] - S[i - 1][j - 1] + (1.0 * A[i][j] - X);
	
	double resnow = -100000;
	
	for (int i = 1; i <= M * 2; ++i) Dr[i].clear();
	for (int i = R; i <= N * 2; ++i)
	{
		Dl.clear();
		for (int j = C; j <= M * 2; ++j)
		{
			while (!Dl.empty() && Dl.front() < j - M)
				Dl.pop_front();
			while (!Dr[j].empty() && Dr[j].front() < j - N)
				Dr[j].pop_front();
			
			while (!Dl.empty() && eps < S[i][Dl.back()] - S[i][j - C])
				Dl.pop_back();
			Dl.push_back(j - C);
			
			while (!Dr[j].empty() && eps < S[Dr[j].back()][j] - S[i - R][j])
				Dr[j].pop_back();
			Dr[j].push_back(i - R);
			
			resnow = max(resnow, S[i][j] - S[i][Dl.back()] - S[Dr[j].back()][j] + S[Dr[j].back()][Dl.back()]);
		}
	}
	
	return (resnow > 0);
}

int main()
{
	ifstream fin("balans.in");
	ofstream fout("balans.out");
	
	
	fin >> N >> M >> R >> C;
	for (int i = 1; i <= N; ++i)
	{
		for (int j = 1; j <= M; ++j)
			fin >> A[i][j];
		for (int j = M + 1; j <= 2 * M; ++j)
			A[i][j] = A[i][j - M];
	}
	for (int i = N + 1; i <= 2 * N; ++i)
		for (int j = 1; j <= 2 * M; ++j)
			A[i][j] = A[i - N][j];
	
	double left = 0, right = 100000;
	while (right - left > eps)
	{
		double mid = (left + right) / 2;
		
		if (canget(mid)) left = mid;
		else             right = mid;
	}
	
	fout << fixed << setprecision(3) << left;
	
	fin.close();
	fout.close();
}