#include <iostream>
#include <vector>
#include <bitset>
#include <algorithm>

using namespace std;

int max_strength(int n, int m, int x, int y, vector<string>& mat) {
    int max_strength = 0;

    for (int rm = 0; rm < (1 << n); ++rm) {
        for (int bm = 0; bm < (1 << m); ++bm) {
            int r_count = __builtin_popcount(rm);
            int b_count = __builtin_popcount(bm);

            int w = 0;
            for (int i = 0; i < n; ++i) {
                for (int j = 0; j < m; ++j) {
                    if ((rm & (1 << i)) && (bm & (1 << j)) && mat[i][j] == '1') {
                        w++;
                    }
                }
            }

            int strength = w - x * r_count - y * b_count;
            max_strength = max(max_strength, strength);
        }
    }

    return max_strength;
}

int main() {
    int n, m, x, y;
    cin >> n >> m >> x >> y;

    vector<string> mat(n);
    for (int i = 0; i < n; ++i) {
        cin >> mat[i];
    }

    cout << max_strength(n, m, x, y, mat) << endl;

    return 0;
}