#include <bits/stdc++.h>
#pragma warning(disable:4996)
#pragma comment(linker, "/STACK:336777216")
using namespace std;
typedef long long ll;
#define all(x) (x).begin(), (x).end()
#define rep(i, a, b) for (auto i = (a); i < (b); i++)
#define each(x, a) for (auto& x: a)

#define debug if constexpr (xdebug) cout << "[DEBUG] "

#ifndef ONLINE_JUDGE
constexpr bool xdebug = true;
#else
constexpr bool xdebug = false;
#endif

int table[500][500];
void update_ans(int width, int N, int A, int B, int row, ll container_area, ll& ans) {
    if(width > B) return;
    stack<int> temp_stk;
    rep(i, 0, N) {
        while(!temp_stk.empty()) {
            int temp_ht = table[row][temp_stk.top()];
            if(temp_ht <= table[row][i]) break;
            temp_stk.pop();
            int length = i - 1 - (temp_stk.empty() ? -1 : temp_stk.top());
            length = min(length, (width > A ? A : B));
            ll area = width * length;
            ans = max(ans, (container_area * temp_ht - 1) / (container_area - area) * area);
        }
        temp_stk.push(i);
    }
    while(!temp_stk.empty()) {
        int temp_ht = table[row][temp_stk.top()];
        temp_stk.pop();
        int length = N - 1 - (temp_stk.empty() ? -1 : temp_stk.top());
        length = min(length, (width > A ? A : B));
        ll area = width * length;
        ans = max(ans, (container_area * temp_ht - 1) / (container_area - area) * area);
    }
}

void solve(int testcase){
    int A, B, M, N;
    cin >> A >> B >> M >> N;
    if(A > B) swap(A, B);
    rep(i, 0, M) rep(j, 0, N) cin >> table[i][j];
    ll ans = 0, container_area = M * N;
    rep(i, 0, M) {
        rep(j, 0, M - i) update_ans(i + 1, N, A, B, j, container_area, ans);
        rep(j, 0, M - i - 1) rep(k, 0, N) table[j][k] = min(table[j][k], table[j+1][k]);
    }
    cout << ans;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    clock_t st = clock();
    int t = 1;
    // cin >> t;
    rep(tc, 0, t) solve(tc);
    clock_t ed = clock();
    if(xdebug) {cout << '\n'; debug << ed - st << "ms\n";}
    return 0;
}