题解

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int n, m, a, q;
    cin >> n >> m >> a >> q;
    
    vector<int> b_values(q);
    for (int i = 0; i < q; ++i) {
        cin >> b_values[i];
    }
    
    int min_b = *min_element(b_values.begin(), b_values.end());
    int remaining_area = (n - a) * (m - min_b);
    
    cout << remaining_area << endl;
    
    return 0;
}