using System;

public class Hello
{
    public static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var n = int.Parse(line[0]);
        var m = int.Parse(line[1]);
        var p = int.Parse(line[2]);
        var q = int.Parse(line[3]);
        var ans = getAns(n, m, p, q);
        Console.WriteLine(ans);
    }
    public static int getAns(int n, int m, int p, int q)
    {
        var a = m * (12 + q);
        var ans = (n / a) * 12;
        var t = n % a;
        if (t == 0) return ans;
        var b = new int[12];
        for (int i = 0; i < 12; i++) b[i] = m;
        for (int i = 0; i < q; i++) b[i + p - 1] += m;
        var pt = 0;
        while (true)
        {
            t -= b[pt];
            if (t <= 0) return ans + pt + 1;
            pt++;
        }
    }
}