#include <bits/stdc++.h>

using namespace std;
ifstream f("balans.in");
ofstream g("balans.out");
int n,m,r,c,v[303][303],x,y,i,j;
double sol;
int main()
{
    f>>n>>m>>r>>c;
    for(i=1;i<=2*n;i++)
    {
        for(j=1;j<=2*m;j++)
        {
            if(i<=n&&j<=m)
            {
                f>>v[i][j];
                v[i+n][j]=v[i][j+m]=v[i+n][j+m]=v[i][j];
            }
            v[i][j]=v[i][j]+v[i][j-1]+v[i-1][j]-v[i-1][j-1];
        }
    }
    for(x=r;x<=n;x++)
    {
        for(y=c;y<=m;y++)
        {
            for(i=n+1;i<=2*n;i++)
            {
                for(j=m+1;j<=2*m;j++)
                {
                    if((v[i][j]-v[i-x][j]-v[i][j-y]+v[i-x][j-y])>sol*x*y)
                    {
                        sol=1.0*(v[i][j]-v[i-x][j]-v[i][j-y]+v[i-x][j-y])/(x*y);
                    }
                }
            }
        }
    }
    g<<fixed << setprecision(3)<<(sol*1000)/1000.0;
    return 0;
}