#include <cstdio>
#include <iostream>
using namespace std;

    #define prec (1<<14)
    #define max_n 305
    int n,m,r,c;
    int i,j;
    long long El[max_n][max_n];
    long long Sp[max_n][max_n];

bool solve ( long long Me ){
    int i,j,k;
    for ( i=1; i<=n; i++ ){
        for ( j=1; j<=m; j++ ){
            Sp[i][j]= (long long) Sp[i][j-1]+Sp[i-1][j]- Sp[i-1][j-1]+El[i][j] - Me;
        }
    }
    long long minim,act;
    for ( i=1; i<=n/2; i++ ){
        for ( j=i+r-1; ( j<=i+n/2-1); j++ ){
            minim=0;
            act=0;
            // initializam "suma"
            act= Sp[j][c-1]-Sp[i-1][c-1];
            for ( k=c; k<=m; k++ ){
                // adaugam coloana actuala.
                act+=Sp[j][k] - Sp[j][k-1] - Sp[i-1][k] + Sp[i-1][k-1];
                if ( act - minim >= 0 ){
                    return 1;
                }
                if ( minim > Sp[j][k-c+1] - Sp[i-1][k-c+1] )
                    minim=Sp[j][k-c+1] - Sp[i-1][k-c+1];
            }
        }
    }
    return 0;
}

 float CB (){    
    long long rez=0,ind=(long long)(1<<20)*prec;
    for ( ; ind; ind>>=1 ){
        if ( solve ( rez+ind ) ){
            rez+=ind;
        }
    }
    return (float)(1.0*rez/prec);
}

int main(){
    
        freopen ("balans.in","r",stdin);
        freopen ("balans.out","w",stdout);
    
    scanf ("%d %d %d %d", &n, &m, &r, &c );
    for ( i=1; i<=n; i++ ){
        for ( j=1; j<=m; j++ ){
            scanf ("%lld", &El[i][j] );
            El[i][j]*=prec;
            El[ i+n ][ j ]=El[ i ][ j ];
            El[ i ][ j+m ]=El[ i ][ j ];
            El[ i+n ][ j+m ]=El[ i ][ j ];
        }
    }
    n*=2;
    m*=2;
    printf("%.3f", CB() );
    return 0;
}