#include <iostream>
#include <cstdio>
#define MAXN 164
#define MAXM 164

using namespace std;

int a[2*MAXN][2*MAXM];
int pre[2*MAXN][2*MAXN], deck[2*MAXM];;
double crt[2*MAXM];
int n, m, r, c;

void citire()
{
	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", &a[i][j]);
			a[i][j+m] = a[i+n][j] = a[i+n][j+m] = a[i][j];
		}
	for (int i = 1; i <= 2*n; i++)
		for (int j = 1; j <= 2*m; j++)
			pre[i][j] = pre[i-1][j] + a[i][j];

}
bool check(int i1, int i2, double x) {
    for(int i=1; i<=m; ++i) crt[i]=pre[i2][i]-pre[i1-1][i]-x*(i2-i1+1)+crt[i-1];
    if(crt[c]>=0) return 1;
    int st=0,dr=-1;
    for(int i=c+1; i<=m; ++i) {
        for(;st<=dr && crt[deck[dr]]>=crt[i-c]; --dr);
        deck[++dr]=i-c;
        for(;st<dr && i-deck[st]+1>m; ++st);
        if(crt[i]-crt[deck[st]]>=0) return 1;
    }
    return 0;
}
//int check(int stx, int len, double k)
//{
//    for (int i = 1; i <= m; i++)
//        crt[i] = crt[i-1] + pre[stx+len-1][i] - pre[stx-1][i] - (k*len);
//    if (crt[c] >= 0) return 1;
//    int st = 0, dr = -1;
//    for (int i = c+1; i <= m; i++) {
//        while (st <= dr && crt[i-c] <= crt[deck[dr]])
//			dr--;
//		deck[++dr] = i-c;
//        while (st < dr && i-deck[st]+1 > m)
//			st++;
//        double scad = crt[deck[st]];
//        if (crt[i]-scad >= 0) return 1;
//    }
//    return 0;
//}

void solve()
{
    int rez = 0;
    for (int i = 1; i <= n; i++)
		for (int j = r; j <= n; j++) {
			/*double k, lo = 0, hi = 1000000;
			while (hi - lo > 0.00008) {
				k = (lo + hi) / 2;
				if (check(i, j, k))
					lo = k;
				else
					hi = k;
			}
			if (lo > rez)
				rez = lo;*/
			int ls=rez, ld=(1<<30), k;
			int lop = j;
			j = i+j-1;
			if(!check(i,j,ls/1000.0)) continue;
			for(int it=1; it<=30 && ls<ld; it++) {
				k=(ls+ld)/2;
				if(check(i,j,k/1000.0)) ls=k;
				else ld=k-1;
			}
			for(;check(i,j,ls/1000.0);++ls);
			if(!check(i,j,ls/1000.0)) --ls;
			rez=max(rez,ls);
			j = lop;
		}
	printf("%.3lf", rez/1000.0);
}

int main()
{
    freopen("balans.in", "r", stdin);
    freopen("balans.out", "w", stdout);

    citire();
    solve();

	return 0;
}