#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];

}

int check(int stx, int len, double k)
{
    for (int i = 1; i <= 2*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 <= 2*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++) {
            int ls=rez, ld=(1<<30), k;
            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);
        }
    printf("%.3lf", rez/1000.0);
}

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

    citire();
    solve();

    return 0;
}