#include <iostream>
using namespace std;
int main() {
    int n, m, p, q; cin >> n >> m >> p >> q;
    p--; q--;
    int c = 0;
    while (n > 0) {
        if (p <= c % 12 && c % 12 <= p+q) n -= 2 * m;
        else n -= m;
        c++;
    }
    cout << c << endl;
}