using System;

namespace yukicoder
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] s = Console.ReadLine().Split(' ');
            int a = int.Parse(s[0]);//目の前の野菜
            int b = int.Parse(s[1]);//目の前の肉
            int c = int.Parse(s[2]);//1つの野菜を食べるための肉の数
            int d = int.Parse(s[3]);//最大数
            int count = 0;
            int n = b / c;

            for (int i = 0; i < a; i++)
            {
                b -= c;
                if (b < 0)
                {
                    break;
                }
                count++;
                if (b == 0)
                {
                    break;
                }
               
            }
            if ( (count*c) + n > d)
            {
                for (; ; )
                {
                    int sum = (count * c) + n;
                     sum -= c;
                    count -= 1;
                    if ( sum< d)
                    {
                        
                        break;
                    }

                }
            }
            
            Console.WriteLine(count);
        }
    }
}