#include<iostream>
#include<map>
#include<vector>
#include <algorithm>
#include<math.h>
#include <iomanip>
#include<set>
#include <numeric>
using namespace std;


int main()
{
    int n, m, p, q, ey, cnt=0;
    cin >> n >> m >> p >> q;
    ey = (12+q)*m;
    cnt += n/ey * 12;
    n %= ey;
    for (int i = 1; i < 12; i++){
        if(i >= p && i <= p + q - 1){
            n -= m*2;
        } else n -= m;
        if (n == 0){
            cout << i + cnt << endl;
            return 0;
        }
    }
}