#include<iostream>
using namespace std;

int main() {
    int n, m, p, q;
    cin >> n; cin >> m; cin >> p; cin >> q;
    
    int month = 0;
    
    while (n > 0){
        for (int i = 1; i < p; i++){
            month += 1;
            n -= m;
            if (n <= 0){
                cout << month << "\n";
                return 0;
            }
        }
        for (int i = p; i < p + q; i++){
            month += 1;
            n -= 2 * m;
            if (n <= 0){
                cout << month << "\n";
                return 0;
            }
        }
        for (int i = p + q; i < 13; i++){
            month += 1;
            n -= m;
            if (n <= 0){
                cout << month << "\n";
                return 0;
            }
        }
        
    }
}