#include <algorithm>
#include <cstdio>
#include <deque>

using namespace std;

class FileInput {
    public:
        FileInput() {}
        FileInput(const char *filename) {
            file = fopen(filename, "r");
            fread(buffer, BUFFER_SIZE, 1, file);
            cursor = 0;
        }
        inline FileInput & operator >> (int &n) {
            while(buffer[cursor] == ' ' || buffer[cursor] == '\n') {
                advance();
            }
            n = 0;
            while(isdigit(buffer[cursor])) {
                n = n * 10 + buffer[cursor] - '0';
                advance();
            }
            return *this;
        }
    private:
        const static int BUFFER_SIZE = (1 << 20);
        FILE* file;
        char buffer[BUFFER_SIZE];
        int cursor;
        inline void advance() {
            ++ cursor;
            if(cursor == BUFFER_SIZE) {
                cursor = 0;
                fread(buffer, BUFFER_SIZE, 1, file);
            }
        }
} cin("balans.in");

const int Nmax = 155;
const double EPS = 1e-8;

int Values[2 * Nmax][2 * Nmax], SumC[2 * Nmax][2 * Nmax];
double SumL[2 * Nmax];
int N, M, R, C;

bool Check(const double t)
{
    for (int up = 0; up + R <= 2 * N; up++)
    {
        for (int down = up + R; down <= 2 * N && down - up <= N; down++)
        {
            for (int i = 1; i <= 2 * M; i++)
                SumL[i] = SumL[i - 1] + SumC[down][i] - SumC[up][i] - t * (down - up);

            deque<int> D;
            for (int i = C; i <= 2 * M; i++)
            {
                while (!D.empty() && SumL[i - C] <= SumL[D.back()]) D.pop_back();
                D.push_back(i - C);

                while (!D.empty() && i - D.front() > M) D.pop_front();

                if (!D.empty() && SumL[i] - SumL[D.front()] >= 0) return 1;
            }
        }
    }

    return 0;
}

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

    cin >> N >> M >> R >> C;
    for (int i = 1; i <= N; i++)
        for (int j = 1; j <= M; j++)
            cin >> Values[i][j];

    for (int i = N + 1; i <= 2 * N; i++)
        for (int j = 1; j <= M; j++)
            Values[i][j] = Values[i - N][j];

    for (int i = 1; i <= 2 * N; i++)
        for (int j = M + 1; j <= 2 * M; j++)
            Values[i][j] = Values[i][j - M];

    for (int i = 1; i <= 2 * N; i++)
        for (int j = 1; j <= 2 * M; j++)
            SumC[i][j] = SumC[i - 1][j] + Values[i][j];

    int Sol = 0;
    for (int step = (1 << 26); step; step >>= 1)
    {
        if (Check((Sol | step) / 1000.0))
            Sol |= step;
    }

    printf("%d.%d\n", Sol / 1000, Sol % 1000);
}