#include<iostream>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, m, p, q;
    cin >> n >> m >> p >> q;
    int mon = 1;
    int sum = 0;
    while (n > 0) {
        if (p <= mon && mon < p + q) {
            n -= 2 * m;
        } else n -= m;
        mon++; sum++;
        if (mon == 12) mon = 1;
    }
    cout << sum << endl;
}