#include <fstream>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <vector>
#include <deque>
#include <limits>
using namespace std;

template <typename Cmp>
class my_deque{
	Cmp cmp;
	deque<int> buf;
public:
	my_deque(Cmp c): cmp(c){}
	void push(const int x){
		while(!buf.empty() && !cmp(buf.back(), x)){
			buf.pop_back(); }
		buf.push_back(x); }
	void pop(const int x){
		if(!buf.empty() && buf.front() == x){
			buf.pop_front(); } }
	int front(){
		return buf.front(); } };


bool exista_subsecv_poz(const vector<long long>& s_part, const int min_len, const int max_len){
	const int n = s_part.size();

	auto sort_by_s_part = [&s_part](const int a, const int b){
		return s_part[a] < s_part[b]; };

	my_deque<decltype(sort_by_s_part)> dq(sort_by_s_part);

	for(int i = 0; i < n; ++i){
		dq.pop(i-max_len-1);
		if(i-min_len >= 0){
			dq.push(i-min_len);

			if(s_part[i] >= s_part[dq.front()]){
				return true; } } }

	return false; }

bool exista_submat_poz(const vector<vector<int> >& v, const int min_r, const int max_r, const int min_c, const int max_c, const long long delta){
	const int r = v.size(), c = v[0].size();
	vector<long long> s_part_col(c+1, 0);

	for(int i = 0; i+min_r <= r; ++i){
		fill(begin(s_part_col), end(s_part_col), 0);
		for(int j = i; j < r && j-i <= max_r; ++j){

			long long la_stanga = 0;
			for(int k = 1; k <= c; ++k){
				la_stanga += v[j][k-1];
				la_stanga -= delta;
				s_part_col[k] += la_stanga; }
			
			if(j-i+1 >= min_r && exista_subsecv_poz(s_part_col, min_c, max_c)){
				return true; } } }
	return false; }

int cbin(vector<vector<int> >& v, const int min_r, const int max_r, const int min_c, const int max_c){
	long long st = 0, dr = 1000010000;
	for(int step = 1ll<<(int)log2(dr-st+1); step > 0; step /= 2){
		if(st+step <= dr){
			if(exista_submat_poz(v, min_r, max_r, min_c, max_c, st+step)){
				st += step; } } }
	return st; }

int main(){
	ifstream f("balans.in");
	ofstream g("balans.out");
	int n, m, r, c;
	f >> n >> m >> r >> c;

	if(r == 0){
		r = 1; }
	if(c == 0){
		c = 1; }

	vector<vector<int> > v(2*n, vector<int>(2*m, 0));
	for(int i = 0; i < n; ++i){
		for(int j = 0; j < m; ++j){
			f >> v[i][j];
			v[i][j] *= 1000;
			v[i+n][j] = v[i][j+m] = v[i+n][j+m] = v[i][j]; } }

	const int rez = cbin(v, r, n, c, m);
	g << fixed << setprecision(3) << rez/1000 << '.' << setw(3) << setfill('0') << rez%1000 << '\n';
	return 0; }