import java.util.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();
		int p = sc.nextInt();
		int q = sc.nextInt();
		int[] arr = new int[13];
		int total = 0;
		for (int i = 1; i <= 12; i++) {
		    if (i >= p && i < p + q) {
		        arr[i] = m * 2;
		    } else {
		        arr[i] = m;
		    }
		    total += arr[i];
		}
		int year = n / total;
		n -= total * year;
		int month = year * 12;
		int idx = 1;
		while (n > 0) {
		    n -= arr[idx];
		    idx++;
		    month++;
		}
		System.out.println(month);
	}
}